I concur, technically no issue!No overlap, seperate files seperate processes seperate memory.

However running two instances does double the work load (maybe). And might cause undue stress on your system resources. ie, running two lgwr, to dbwr etc...

For example, A "bad" impact is if the disk subsystem for redo logs are now saturated, IE both instances log to the same physical disk. That would be a "BAD" impact. This all depends significantly upon your hardware.

YMMV