You can sign only one petition.
If you sign more than one petition for the same position, your signature will be invalidated on all petitions and will not count for anyone.
So Primo's volunteers, although they did not mention the primary, did ask if people had signed any nominating petitions.
Because it's really not a primary-specific question - even if Primo were unopposed, someone from the other party could have asked the person to sign.
Primo's volunteers discovered that some people had already signed the challenger's petition, but there did not seem to be a coordinated, organized approach to getting signatures.
(Primo pays to use the party database, which indicates who has voted in which elections and has a measure, if known, of where the person is on the political spectrum. We use the lists to decide, block by block, which doors should be knocked.)
Primo's opponent texted him this morning:
I want to let you know that we have had numerous reports while collecting signatures that people who signed your clipboards did not know there's a primary, and that they didn't know they could only sign for one of us so they signed for both. Since that nullifies those signatures, I thought you should know the volunteers didn't seem to understand that. My people halted that whenever possible so that your signatories didn't sign ours and negate your signatures. We sure wouldn't want to end up with duplicate signatures so I wanted to let you know.
Apparently, the challenger's volunteers did not know to ask if someone had already signed.
Which is the correct process.
But no - why on earth would Primo volunteer that there is a primary? The primary is not relevant to any of this. Primo has to collect signatures whether or not there is a primary.
Primo and his volunteers asked if people had already signed. They know quite well that multiple signatures render the duplicates void.
That's all you need to ask.