Learn the DTA code? Probably not... it is the XMP IR protocol and most remotes cannot learn all of the commands. Typically IR signals are designed so that the durations of the on and off times signify zeros and ones. But XMP has 16 different durations, corresponding to the hexadecimal digits 0 through F, and it is notoriously difficult to learn.

Setup code 0476 and 1376 are the General Instruments IR protocol. It is not related to XMP in any way. The DCX3400 (a full set top box) responds to both Cable 1982 and 0476/1376, and apparently so does the DTA100.

Perhaps there is a way to tell the DTA100 to ignore the GI (0476) signals, but I don't know what to try.