Rookie question from a part time illustration contributor to istock.
I've been with istock around a year and want to start uploading to other sites, and maybe leave istock as the new compulsory partner programme will screw us lowly non exclusives. What's normal practice regarding identity? Do you normally upload the same/different designs under the same/different name on different sites?
What are the pros and cons?
Thanks in advance.

I have the same name everywhere except 123rf because when I started with them, they made the account and loaded images from DVD, so they made joannsnover and I'm jsnover everywhere else.

Many times you end up with different images at different sites because of differing editorial policies - SS likes raster illustrations and IS for the most part doesn't; DT has stringent restrictions on similars from a series, so they'll be missing images others have, and so on. If you do vectors, look at each site's pricing scheme to decide if you're happy with it. For all sites except iStock you can upload JPEGs from your vectors if you don't want to sell the vector originals.

I like to think that people would know my work even if I changed my user name from one site to the other If a buyer shops at one or two sites - SS and IS, for example, it'd be nice to make it easy for them to find your portfolio wherever they're shopping that particular time.

I use one name now... almost.  Nine of 10 sites allowed me to change/uniform my account names.  Only 123 can't figure out a way to do that. 

For branding purposes, one name is best, and it helps to first make sure it's a name that could be a web domain if you choose to do a website at some point.  That way a potential buyer on any site could see one of your images, and later remember your contributor name, do a web search on you and find your site.  It would make sense to at least have a landing page under that name with samples of your work and links to the agency sites (make them referral links that could get you some money from the sites that offer a referral program... most do.)