From my understanding there is an electronic database of "stamps" that many, but not all (Ukraine was one, don't so any longer) participate in. In light of this it is possible that there could be an issue. We have to remember that the program is to get people the people IN Ukraine out of harms way. Honestly, like what Boiler said, I highly doubt anyone is going to check this. Especially in light of many of these people now have no home to return to.
-Eric