Cvs add: X added independently by second party

[Brook Milligan <brook%nmsu.edu@localhost>]

I went to add a buildlink3.mk file to the lang/R-cpp11 package.  I get the following message from cvs:

# cvs add buildlink3.mk 
cvs add: `buildlink3.mk' added independently by second party

I presume this means that someone added the file, but never committed it; perhaps it was even me having gotten sidetracked in the middle, which often happens.  Is this the correct interpretation?  At this point, how can the file be committed?

Cheers,
Brook