new chamberlain remote for C203C opener is opening my other garage door at same time

I have 2 garage doors, both were serviced by vintage Wayne Dalton (1993 or older) units that are actually Chamberlain openers. The circuit board on one was acting up (took several, random attempts to fully open or close door), so I replaced it with a new Chamberlain C203C, yesterday. All went fine until I programmed the remote; activating the remote caused both my new unit the other old WD unit to open at the same time.

I operate the other WD with Liftmaster 375LM 2-button remote, and that still works fine and does not interfere with my new opener. The 375LM has both a programming button and dip switches, but the WD unit does not have dip switches--it is an early "smart" unit with a "learning" button.

When I spoke to Chamberlain's support today, their only solution was to replace the older WD with new Chamberlain! This sounds like a solution designed by the Marketing department rather than Engineering?

Any ideas?

Thanks

Clear out the radio receiver on one of the operators and reprogram the remote. You usually can clear the memory by holding the "Learn" button for 10 seconds or so.

Actually, I tried that on both, including unplugging the old Wayne Dalton whilst programming remote on new unit. Nada--same problem.

I spoke with someone at Chamberlain a couple of days ago. They are not able to "solve" the problem either due to vintage of my old device, so they are sending me a new unit to replace the old one--gratis. A generous alternative, but probably a lot cheaper than having engineering department redesign their remotes to address this issue. They say this happens from time-to-time.