It's always best to keep things simple, to reduce complexity is to reduce problems.
Since your 1050 Ti can support two monitors, there is no need for a second GPU if you have two monitors.
If the real reason you want to do this is so you can get some use out of your old card, don't bother. The card is a 'sunk cost'. It's been paid for and used. You got your use out of it. There's no financial benefit if you figure out some janky way to use it. Sell it if you want to squeeze every bit of value out of it.