You might be at dev system. try below things at dev system.
Just go ahead and create two simples chains to load data into info objects.
use same variant at info pack levels for two chains and see it.
if you won't any issues. its clear to use same variant at multiple times.
While using same variant at 2nd process chain design time you will know that.
if won't allow it may give error. if there is no error - it means allowed .