Simply set the World TV box to output on different channels than the Dish box uses, but on the same band, i.e. both set to antenna or both set to cable and set up different output channels (separate by at least 2 channels) channels if possible, use a splitter to combine the feeds.
Diplexers and triplexes are not a problem as long as joining of RF outputs is not done in the part of the cable that carries both RF and satellite feed.
Diplexers and triplexes are not a problem as long as joining of RF outputs is not done in the part of the cable that carries both RF and satellite feed.