I see failures on both ends here.
The master you sent him was inadequate. Sending .wav files with file names is something I have never done, and would never do.
You need a "Master CD" to send. Not just "mastered" songs. I prefer DDP2.0 or if they cannot support DDP2.0 just an audio CDR with all fades, track pauses, indexes, ISRC codes, dithering, etc exactly how you want the master to be. DDP2.0 has less possibility of data corruption as compared to audio CD master. Audio CD has no sort of error correction, so make sure to use a good quality CD and burner. Also a detailed PQ sheet with all the previously mentioned info as well as contact info so the manufacturer can contact you should any problems arise.
Also mention on the PQ sheet for them to not to apply dither, or any sort of normalization, or in any way tamper with the data. If they find your master unsuitable for any reason (and they should not), they will need to explain the issue and have you correct it, not them. They replicate, not master.
Oh and don't worry about the RMS or Peak levels of what you send for replication. That should not matter to them one bit. Although it sounds like maybe they just sent you duplicates maybe, that is usually the cheapest.