One option for the Perl family would be to consider moving the numbers to the left. For example, 5Perl and 6Perl, which can on their own have major, minor, and patch numbering.
So, for example, the next release of 5Perl would be 5Perl-6.0.0. That way, there would be little confusion about which language it is.
I’ll take the liberty of channeling Michael Bolton (not that one) on behalf of Perl 5: “Why should I change? He’s the one who sucks.”
It seems Perl 6 is changing its name. Now, I hope Perl 7 can pick up from where Perl 5 left off.