Blending lager yeasts may be a little futile since, ideally, you'd lager out all the yeast flavors and be left with a "clean" malty beer. Of course, in the real world, there's always some flavor contribution, even from lager yeasts. I'd say that if all went well, you wouldn't notice a big difference between the beers fermented with either of these yeasts and one with a blended yeast, at least not after lagering had cleaned things up.
That being said, I pitched 2 different yeasts on a lager to build up slurry for a couple of different brews. When it came time to a big batch, I decided that it had been sitting too long and neither pitch alone would be a high enough cell count. I ended up pitching all the slurry from both yeasts - S-23 and 34/70. Early on there had been a difference in the beers but it didn't take long for them to become more or less indistinguishable. Now with the blend, it just tastes like a young lager that's not cleared, but even before the yeast is dropped, it's tasting less fruity than the early samples of the starter batches.
I think cell count in the pitch will probably have a bigger impact on flavor and attenuation than pitching relatively similar strains.