I think the 15-1995 transmits both IR and RF and is supplied with an RF to IR coverter. I assume that RF to IR converter is positioned to operate the downstairs Dishplayer and that position (intentionally or accidently) also operates the downstairs TV.

So the objective seems to be to make a 15-1995 operate the upstairs TV by IR and the downstairs Dishplayer by RF, but not operate the downstairs TV.

Maybe the solution is moving the RF to IR converter so it can't affect the TV. Maybe it would take a more complicated solution.