Currently trying this with a Flanders Red/Lambic-type beer - half with Roselare, and half with a concoction of dregs. Otherwise the fresh strains in the Roselare take up too many sugars/nutrients and give off too much acidity to revive the several strains from the dregs.
Also gives me some room to blend, hopefully creating a Flanders and a lambic from the same wort. We’ll see.
Update - the beer tastes pretty good. It fermented out all the way, and has a pretty good flavor.
Denny & Ron - I will say that I think you were right all along…I think I would have been better off blending as it isnt’s quite what I was going for. A blend of the two beers fermented with different yeasts IS the way to go. Doing it this way, I am tied to whatever the final outcome of the fermentation is. Through blending at different amounts I think I might find that balance I am looking for.
Though the beer isn’t bad - I have serious doubts it is the best it can be. Good call guys, thanks for the advice as I will be taking it my next batch 
looks like the boston beer company tried mixing ale and lager fermentation as well. We’ll see how successfule they were later this year. https://www.drinks-insight-network.com/news/samuel-adams-launches-sam-76-us/
The only time I have used two strains is when one strain did not take off or finish completely. I wouldn’t try this but if I wanted the best of both worlds I would probably blend the beers.
What I have been thinking of doing lately is doing a 5 gallon batch along side a 1 gallon batch, I have 4 1 gallon fermenters, this could be a fun sour project with blends.
The only time that I’ve ever mixed lager yeasts is when I’ve started my brew day and realized that I don’t have enough of one strain to pitch.