There have been multiple groups that have used this name.
1) Undercover was a Hard Rock/AOR group by a ex-Vandenberg singer Bert Heerink from Netherlands who make 2 albums in the 90s. One was Undercover (1990), a cover album, and second record was All Line Up (1994).
Bert Heerink Vocals
Dick Kemper Bass, Vocals
Ronald Bekking Guitars, Vocals
Ivo Elfers Drums
Cyril Whistler Guitar, Vocals
2) Undercover was a UK based pop-house group who hit the UK #2 spot in 1992 with their Stock, Aitken, Waterman produced cover of Baker Street. Read more on Last.fm