Can you get shingles on both sides of your buttocks at the same time?

Absolutely, but very: rare. Shingles is essentially always expressed along distribution of peripheral nerve fibers, dermatomes, on one side. It is extremely rare (reasons unknown) to express on both sides, in the same or very similar distribution. If the distribution does not follow dermatome pattern, then also very inconsistent with Shingles. Thus what you are concerned about is unlikely to be Shingles.