is there any reason to prefer using Win32::Socketpair over it?

It depends whether you're asking about the interface or the implementation.

I don't know what differences there might be in the implementations, but winsocketpair is obviously easier to use than socketpair.

my ($fd1, $fd2) = winsocketpair();
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vs

use Socket qw( AF_UNIX SOCK_STREAM PF_UNSPEC );
socketpair(my $fd1, my $fd2, AF_UNIX, SOCK_STREAM, PF_UNSPEC)
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(Just to make things confusing, it has has to be a UNIX socket, not an INET socket.)