to be a double dipper, one must have appeared in a major league game for the dodgers (or other incarnation of the franchise), left the franchise (usually spending some time playing for another team), and then have returned and appeared in another big league game for the team. that's how most become double dippers. there are some who missed out on the label because they played, left, and returned, but didn't get to play for the dodgers a second time (eg. ramon martinez, willie crawford, tommy lasorda among others) or they were drafted by the dodgers but didn't play for them before leaving, but eventually returned to the club (guys like scott proctor, ted lilly, shane victorino, and ron coomer). and then there are those who play, leave, and return without having actually played for anyone else (joe moeller and denny lewallyn come to mind). johnny allen fits that bill.
here's allen's 1990 target card. pretty sure it's the only card i have of him.by all accounts an ornery cuss, allen twice led the american league in winning percentage - he was 17-4 (.810) as a rookie with the 1932 yankees, and 15-1 (.938) for the 1937 indians. he suffered an injury during the 1938 all-star game, and his career began to decline as a result. prior to the 1941 season, after a couple of subpar years with the tribe, allen was picked up by the st. louis browns. the browns waived him after he had a 2-5 start and a 6.58 era to start the season, and the dodgers claimed him. he finished out the 1941 season with brooklyn, going 3-0 with a 2.51 era. he pitched for the dodgers again in 1942, going 10-6 with a 3.20 era, 5 complete games, and a shutout, but his temper and antics (including an incident in which he took a run at an umpire that resulted in a 30-day suspension) may have been too much for the dodgers as they traded him to the phillies in december of 1942 for rube melton.
the dodgers had a change of heart, however, and in april of 1943, they purchased his contract and brought him back into the fold. at least until july, when they traded him away once again, this time to the new york giants, and this time for good.