premise: Darrell Abbott (August 20, 1966 – December 8, 2004), also known as Diamond Darrell and Dimebag Darrell, was an American musician and songwriter who was a co-founder of Pantera alongside his brother Vinnie Paul, and founder of Damageplan. He was considered to be one of the driving forces behind groove metal.
hypothesis: Pantera and Damageplan were two bands active at the same time.
reason: The text mentions Darrell Abbott was in both bands but does not specify his active years in either or which years the two bands were active.