Unlikely. Generally, UPS or whatever will hang onto them until Friday.
And all they would do is run apps like Geekbench, and that would tell them 4 GB RAM. If people are claiming Geekbench and Antutu are wrong, it would be hard to prove without a teardown or else some other very specific software.
This is ancient history, but FWIW, I got my iPad Air 2 a day before almost everyone else did, and using existing apps confirmed that it had 2 GB RAM. (Mine was one of the few that slipped through, so I got my iPad Air 2 on Thursday even though official launch day was Friday.)
Before that, no 2 GB iDevices existed.