if 2 mining app use same gpu it will crash and gives bluescreen error. then rebooting xd
Not likely.
What you will most likely experience when running two mining programs is a fraction of the hashrate you would achieve mining each algorithm separately. If this total adds up to more than you would get from mining each separately or not is up to you to figure out, but the basic concept is the same as what dual miners such as Claymore's perform internally when dual mining.
Before Claymore combined this functionality into a single miner a lot of people would do just that running separate instances of Sgminer with each instance running a different algorithm. This works best with algo's that utilize the GPU in different ways. For example Decred and Ethereum mining works well, trying to mine two Ethash (Dagger Hashimoto) algorithms such as Ethereum and Expance will not work well and would result in problem less overall hashrate than running a single instance. You will have the best luck combining a memory intensive algorithms (such as Ethereum) with a computational intensive algorithm such as DCR or SIA.
I think Zcash and ZMR would tax the GPU in similar ways and might not make a good match up. However, as I said earlier it shoudl cause any harm in trying and the best thing to do is experiment for yourself and see what your results are like.
