IMO it doesn't matter, learning go from Java should not be what excludes you from an offer. Of course if the employer has a choice between two otherwise even candidates then maybe it'd help.
I think the problem is working with both in a production environment is what is going to set you apart.
I'd say learn a language that's really different like a functional or a logic language.
Otoh I've not been interviewing lately so maybe my take is totally off base