I got an open tin of Meridian and an open tin of Abingdon. Two amazing Balkans and one 6 oz jar. So to save space dump them together. Who else does that? I do not see any reason why you wouldn't if they taste basically the same.
It's your tobacco and if you want to blend them together, it should be no issue. I have a tub that I throw any remaining tobacco from tins into when there is not enough left for a full pipe. There is about two pounds of tobacco in it that has accumulated over time. The blend is constantly changing. Sometimes the blend is awesome, sometimes not so much. But it is always an interesting smoke. We all have certain nuances in the way that we handle tobacco, whether it be how we pack a pipe, light the tobacco, or store tobacco. No one way is the absolute written law on how it should be done. What works for one person may no work for another. But at the end of the day, as long as you are happy, that's what really matters.
Sometimes two blends taste the same but when a palate chages (and it surely does sooner or later) they suddenly become different. That's why I never put similar blends in the same jar. If it works for you that's the way you should do it. A limited space can sometimes indeed be problematic.
You don’t have enough space for 2 jars? Where the hell do you live? In a tuna can?
Otherwise, do what you like. I will sometimes mix things, but rarely will I mix Latakia blends, as those complex components can create such differen flavors when mixed. Sometimes a dash of a Turkish can create a whole new incense like aroma, yet when a little more of this or that is added, it might turn into a farty aroma. I feel more comfortable mixing things with less components.
I sympathize with the tendency to save a little space and consolidate jars. However, these blends are rigorously and artfully done, and usually they won't be improved by dumping them together. I do my mixing in a separate ceramic bowl, maybe a few pipe bowls at a time, and I try to keep the flavor tweaks simple, adding a single-leaf condiment or two to a single-leaf base, or to a blend. I would on occasion do as you have done, taking two Balkans or similar blends and putting them together, but only a few bowls worth, not a whole jar, so if it is simply harsh, muddy, or otherwise bad, I won't have a whole jar full. I try to do mixing thoughtfully and with some restraint, and have had some pleasing results. The dump-it-altogether approach I have more often found nasty.
On the opposite, custom made mixtures will actually work better. It is like saying here is your steak and we put two drops of hot sauce, no more no less. It is perfect with just two drops. I think I know better how spicy or bland I like my steak.
One thing I discovered is that 70% Mississippi River and 30% Old dark fired may be the perfect tobacco for me. Experimenting is good, really it is. You may discover the combination that is perfect just for you.
It's your tobacco to do with as you please. I personally don't like to mix balkan style blends. I only mix when I think there will be a benefit, not because I have one jar. I am sure that I have missed opportunities somewhere along the way, though, too.
I had an old, opened tin of Dunhill Flake, Mac Baren Navy Flake, and SW Full Virginia Flake that I combined into one jar.
Not my normal practice, but in this circumstance it made sense given the small amount of volume remaining in each tin.
I’m intrigued, yet somehow deeply disturbed by the thought of these huge jars full of dozens of different types of leftover tobaccos all thrown together that people so often talk about. I can’t imagine what a casserole of nonsense that must be, and I don’t know if I’ll ever be brave enough to try it myself. But for you brave pioneers smoking into the unknown, god bless you. You guys are the Chuck Yeager’s of pipe smoking.