Do what he said. go to antennaweb and wrigte down all channel numbers and set tv2 to a channel number not listed on that page.
use a two way splitter backwards to combine the ota and the tv2 into one signal, do this right by receiver and before signal goes into diplexer, other room, etc.
you may have to use a separate two way splitter to split the ota signal that comes into this room. so many splitter may cause weak signal so an amp may be necessary or an uneven splitter called a "tap" that will allow more of ota signal to go to tv2 instead of into receiver.