Uniform assortment question

[Sinewgrab]

So, what precedent is there in the late 1800's for militaries having very different uniforms in various units?  I was considering mixing in a bunch of british uniforms painted in my Norwegian blue with the WW1 Belgians I have been using as my main infantry force, as I had been collecting them to use, and I just can't get excited to paint redcoats.  Am I going to be blowing all sorts of conventions out of the water if I do this, or would mixing one infantry uniform with another based on branch or such be within the bounds of doctrine?  I believe I can call one 'tropical dress' and the other standard gear, but I don't want to get too far away from reality in my science fiction.