Nothing earth shattering here. I made longer crates with a little different style. I am considering making small ones two for variety, and perhaps a few other styles of crates for the same reason.
Here is my reference:
As a side question: is there a way to Cut a model in half to get two separate sides?
Nice crate reference what is it from? Period wise.
Good reproductions too.
You ned a cut line. To halve it. Loop cuts might do it, but you may need to line them up by hand.
Or a bug cube and Boolean half away, then repeat for the other half.
Depends on what you are aiming for, a half crate? Might not be a simple, or simpler, as cut in half. You could remove the middle upright and just scale it along the length.
If things are symmetrical, do use the mirror modifier! You can even mirror on X-ax, AND Y-ax. Or even using the Z-ax also.
The best is to use one ax for your purpose. Make two different (mirrored boxes). Then you are able to make 3 designs. Box A., B. and AB.
You can also use the boolean modifier, but I think it is a bad sollution.
For a project, I went for a different solution. Using 1 crate but with different sides. Rotating the box to show a different type. You have six sides to design 
Both suggestions have their merit.
For @NP5 : I think cutting it away with a Boolean would be an interesting method. I was thinking of cutting it just before the middle of the e and then mirror it into a small square box.
The period? I don’t know to tell you the truth. All I know is that it looked liked like it would fit my idea. Old or new, if it fits, I take.
For @FedPete : Cute Cube 
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I suppose one approach it so that each side is very unique. This seems particularly good for quick screenshots, but what about for game design? Of course for static objects this would be acceptable, but for maneuverable one?
In general, had I built a smaller box and then doubled it or mirrored it I could have made a modular box set that could be used to build larger boxes.
For game design, the mesh will be simple (the same), but the texture diffuse, normal maps will differ.
