You either need to upload a valid model release or else sell the image as RM with no release. Alamy requires model releases for any visible people whether or not they could be identified if the image is RF.

If you sell the image RM at Alamy then you need to remove it from any sites where you are selling it RF.

I can't find anything related to this when googling: how to submit an image that has 2 people on the image who are practically unrecognizable???

You are not supposed to upload it as RF if you don't have a release.
These 2 may be practically unrecognizable but theoretically they might be recognizable from the context.
On Alamy if you don't have a release you are not supposed to upload as RF even photos containing body parts, as hands, legs, etc. Even if the person is far away and 5 pixels tall, these 5 pixels count as a person.
You can submit it as RM. This is Alamy. Dura lex, sed lex.

Read this:
http://www.alamy.com/Blog/contributor/archive/2008/02/25/2681.aspx

I had a very similar case when I started on SS in 2008. I submitted a commercial photo, the inspector accepted it but changed it to editorial (there was no requirement about the editorial caption back then).

They want a release if only a body part is visible.  I had an image of a hand holding a pair of chopsticks.  After a year or so they came back and said it was a "people" shot and had to have a MR.  I told them to take it down as it was selling well elsewhere as RF with no release required and I wasn't about to supply one for something as idiotic as this.