It looks like the L in Elvis' name has the same imperfection as the first L in "Campbell," and the little nick off the first E in "Presley" is the same as the nick on the E in "Burgess," though I guess there could be other reasons for that.
This poster sold for almost $10,000. at a recent Heritage Auction and it's a fake! It's supposedly from March 19, 1955 but the lineup (minus Elvis) was from a show on March 19, 1966. (Nat Stuckey was on the bill where Elvis name is, but collectors don't pay much for Nat Stuckey items) Among the many things wrong with it - Texas A&M wasn't called Texas A&M in 1955. The first three artists on the poster were exclusive to the Grand Ole Opry in 1955. Wilma Burgess was 15 years old in 1955 and didn't sing or enter a studio until 1960. Great fact checking Heritage!