Laptop drops wifi when moving from one WAP to another one, with same SSID
i have had this exact issue with 2 SSID's with the same name.  i believe airport uses some kind of UUID for each AP, and gets confused wehn it see 1 ssid with two different id's.  you can do it with cisco (etc) gear where the ap's are part of a managed network.  but i never got it to work well when there were 2 with the same name.

you could try deleting both from the known networks and try to clear out some of the old info.