usually not but it depends how big the places are and if they are in data base. I remember reading soing paul put on here about a subject data base or soing and the ability of clinics to get that information. It couldnt hurt to screen though......
a few places check. like in kc where there are 3 or 4 labs they check with each other. but there's paperwork you sign that informs you.
also there's a guy promoting a service to do these checks, there's a post on it from martin, but i doubt most places are signed up. the fda could notice if they bothered, but i havent heard of the fda labratting anyone out.
paul strongly discourages this practice. i take no position on it myself.