The Eagles came from behind to lead as Campbell scored a second-half brace, but Kendall Watson equalised with 12 minutes remaining as Palace maintained their unbeaten start to the summer schedule.
Andros Townsend had a hand in both Palace goals as Alan Pardew experimented with a 3-5-2 formation, but assistant manager Keith Millen was disappointed with the manner in which Palace surrendered the advantage.
"We really enjoyed the game," Millen said after the game. "We weren't happy with some of the goals we conceded but for the fans I was pleased that there were some goals in the game. It became very end-to-end but that happens when you make a lot of substitutions."