i’ve never tried it myself and wouldn’t recommend to, in no way it’s “safe”, i guess it will cause some trouble sooner or later.
if you just want to use your wallet (spend/receive coins) on multiple machines, there’s ways to make it portable (i guess, also not tried yet).
if you want to generate on multiple machines, that’s possible by using a single client/wallet and multiple miners (GPU, CPU) running on the same, or multiple remote machines.