1/2 the coins that could be mined with dual mining are now mined by ASICs which no GPU can compete with. The other 1/2 are more are less coins that were created to just exist. Occasionally some will spike in price for a couple days but nothing meaningful.

Do your own research and see if there is a coin you thing has a purpose or value that cannot be solved by another coin. If you find one dual mine it with hope it might go up later. For now nothing is really worth dual mining unless you have free power/cooling and are willing to stress your card more than it has to.