I'm no expert on the Greek, but in scanning a number of different translations, I see that some render the verse as does, for example, the ESV:
Greet Andronicus and Junia, my kinsmen and my fellow prisoners. They are well known to the apostles, and they were in Christ before me.
The NET Bible reads similarly, as do several other translations. The commentaries I checked (Barnes' Notes and Believer's Bible Commentary) support the idea that Junia and the others were persons of note, well known to the apostles, but not necessarily themselves apostles.