Action Comics #591 1987

Action Comics #591, published in 1987, features Superman journeying to a "pocket universe" Smallville, encountering a Superboy and Krypto he doesn't recognize. This leads to a clash between the two Kryptonians, orchestrated by the villainous Time Trapper, who created this alternate reality. The issue is notable for its role in redefining the Legion of Super-Heroes' origins in the post-Crisis continuity, exploring the complexities of time travel and alternate histories within the DC Universe.