Probably yes, though you may or may not face the rejection of 'too similar'. On the landing page of each image, down towards the bottom there is a 'similar images' section. I'm not entirely sure how their algorithm knows which images are similar, but I strongly believe one of the many criteria they use is 'time'. That is, if obviously similar images are uploaded too far apart in time, they might not show under 'similar images'. Obviously my opinion is just speculative. 

On the other hand, the obvious answer to delay upload of similar images is that images uploaded later might be more likely to be found by buyers at a later time. While images no matter how old all tend to sell, I believe their search engine has a slight bias towards newer images.

If you do a series it makes sense not to upload more than half a dozen in one hit as it's pointed out above they can be rejected for similars.

Also too many of the same subject uploaded at the same time can compete with eachother for the same sale.

Great advice .... I'll be dividing up my submissions more in the future......

The other thing I should have pointed out is that if the images you upload are successful you can always add more images at a later date and perhaps boost sales for the shoot when the initial surge dies off.

The reason I ask is I just discovered that there is a keyword "in a series"

Ιf i may comment, "in a series" maybe can have multiple meanings.
Perhaps it does not mean variations but indicate something like:
Ten shots of ten different houses in a same archietecture building style or block?
Twenty shots of  four models posing one by one, then in couples and then by three in every shot?

Just a guess

I am a little late with my answer, but well... be careful with series if there are too many images in one series.

I got an email on 25th of july from getty, that my submission limit has been set to a maximum of 50 images per week for the next 3 month, due to 'similar images'.

Original Email:
Hello,
 
Hope this email finds you well. We�ve noticed a trend in your account�when uploading files, there appears to be a significant number of duplicates or files that are too similar to each other. The following is how we define duplicates and/or similars:
 
�   Uploading a set of nearly identical files to your portfolio.
�   Reprocessing a file already in your portfolio (changing colors, adding filter effects, etc.).
�   Flipping a file already in your portfolio and submitting it as though it is new.
�   Recycling files or image elements already in your portfolio to create new files.
�   Cropping horizontal or vertical files to square or panoramic and submitting as them though they were new.

To assist you in being more selective with your submissions, we�ve placed a file submission limit on your account of 50. This means you will be able to submit a maximum of 50 files per week. To view your submission limit usage and the date it resets, visit your profile page under, �ESP User Info� (https://esp.gettyimages.com/app/profile).

And i did none of those 5 'mistakes' up there, i tried to explain that to them and got this answer:

Original Email:
Our editors would like some time to monitor your submissions and ask that you reply back in 3 months (after Oct. 24th) to review your submission limit.
 
Our general guidance is to select no more than 2-4 different variations.
 
Thank you for your understanding.
 
Sincerely,
Contributor Relations


Now i am trying to get my submission limit removed, but they don't answer and the ticket system does not work anymore.

Good Luck

Wow, that's a little scary. I appreciate your sending this along to me. Hope you are able to get that limit taken off soon!

Just to inform you about my experience with "images in a series" (i wrote about a submission limit before in this thread), i receive an email from istock support today, which says:

---------------- Original EMail --------------------------------
Thank you for your message.
 
It appears you are still submitting serial/duplicate content but in separate batches.
 

iStock defines duplicates and/or similars as:
 
- Uploading a series of nearly identical images to your portfolio.
- Making minor alterations to an image already in your portfolio (e.g., changing colors, using the same background but changing the text, etc.).
- Flipping or mirroring a previously approved image horizontally/vertically and uploading it as a new submission.
- Creating a series of images with visually minor variations
 
Offering different versions of the same file can be useful - however, we suggest a limit of three or four of the strongest compositions and not submitting any more than that. When uploading different versions of compositional work, please avoid making minor alterations such as mirroring objects, moving/adding/removing small elements that aren�t immediately apparent to the viewer, small color adjustments, etc.
 
Unfortunately we will be unable to increase your submission limits until you are able to demonstrate your understanding of our self editing guide.
 
Self-editing Guide: https://contributors.gettyimages.com/article.aspx?article_id=4861
 
You�re welcome to request an evaluation of this, six months from the date of this notice (on or after May 29, 2020). To do so, please submit a support ticket: https://accountmanagement.gettyimages.com/Help/SupportTicket
 
I will go ahead and close this ticket. If you would like to reopen this ticket, please reply to the email notification of my response as replies via Account Management will not register a response if the ticket is closed. If you have another question or issue, please create a new ticket as we often need to assign tickets to different people and departments.
 
Sincerely,

------------------------------------------------------------

After saying i am duplicating images and uploading them, i waited their three month to get a new submission review to get the submission limit removed again.

Now i got another 6 month for "images in a series" submission limit, like shooting sightseeing images at night in London (thats what they called duplicates).
So now i quit istick/getty - thats really a joke...