127.0.0.1 may well be being interpreted as the remote machine, not yours - what happens if you explicitly use either your machine's name, or a non-127.* address?

Update:

Further poking around reveals that RegSaveKey and RegLoadKey are defined in Win32API::Registry, which mentions the following:

WARNING:  Loading of hive files via a network share may silently
corrupt the hive and so should not be attempted (this is a problem
in at least some versions of the underlying API which this module
does not try to fix or avoid).  To access a hive file located on a
remote computer, connect to the remote computer's Registry and load
the hive via that.

Which seems to imply that it is possible to do this remotely.