One sees it all the time in the instructions, that all batteries used in the device must be the same brand.
Say I have three Evereadies and one Duracell - all fresh, and all the same strength/price. Other than possibly voiding the warranty, what other reason would there be not to use the one mismatched one?
If the cells all output the same voltage, you should be all right. However, battery brands tend to run down at different rates. Any cell outputting a higher voltage than the others has the possibility of overheating. Technically, if you have a multi-cell device you shouldn’t even mix old and new ones of the same brand and type.
But my guess is that differential heating is a minor enough problem to ignore it altogether. I’ve been mixing brands and ages for years and have never had the batteries misbehave in any way other than running down. And I have not noticed that they run down any earlier, though I do agree there’s reason to expect at least some tiny difference.
Brands might differ in whether they work better at high load or at low load, and in how long they can be stored in various states of charge. Yet, although these details ought to suggest using one brand in your wall clock and another brand in your portable shaver, I’ve never heard of anybody even exploiting this very first pass of sensitivity to brand strengths and weaknesses.