You should not use copies of the same wallet.dat simultaneously on multiple instances. The wallets create a new set of keys from time to time, and two different copies end up unsynced from the keysets so that you might be missing balances from some of the wallets even thou the coins are there. This goes with all bitcoin-qt based clients and their wallet.dat:s, not just USDe. It might work just fine for some time, but probably not forever and not worth the risk.
EDIT: ONE WALLET PER ONE DEVICE AT A TIME!
So does that mean that it's ok to use the same wallet.dat file on multiple devices as long as it's not done simultaneously?
Not entirely, if you switch between two copies that you frequently use it's as bad. Only situation when a copy of the same wallet should be used is when restoring a backup and the other copies of it will no longer be used on other installations.