My understanding is that there are two (2) different versions of the Measy A5A.
The old Measy A5A
have 512 MB RAM and run Android 2.3 on the Rockhip soc.
The new Measy A5A
have 1 GB RAM and ship with Android 4.0 on the Allwinner A10 soc.
Two different firmwares for each.
Other than that, both are the same garbage.