Can buttock pain on both sides be sciatica or herniated disc?

It is possible if the disc bulges or herniated centrally rather than on the right or left.

Bilateral pain emanating from the lumbosacral cistern could be due to a large central herniation, but could also be seen in degenerative spondylosis with bilateral foramenal stenosis. However, you could alternatively possess sacroiliac dysfunction, which indeed is often bilateral.