The former Premiership official has made a habit of courting controversy and in a partisan atmosphere, he sent off two Barnsley players and infuriated the home crowd.
Indeed, he spoiled what could have been a decent spectacle for an attendance of over 12,000 with a dreadful display of man-management.
Doncaster had started well and lively midfielder Paul Green had fired just wide on four minutes.
The warning wasn't headed by the Barnsley defence and nine minutes later a long ball forward found James Coppinger and his cross eventually found its way to Green 15 yards out and this time he made no mistake with a right-foot shot.
After 18 minutes Barnsley defender Neil Austin and Coppinger were involved in a push-and-shove contest on the touchline.
Coppinger fell over the wall surrounding the pitch and Rennie immediately flourished a red card to Austin.
Barnsley should have been level on 41 minutes when a terrific cross from Chris Shuker picked out Barry Conlon but his header from six yards went straight at Rovers keeper Jan Budtz.
Just as the second half appeared to be settling down, Rennie again took centre stage.
On 73 minutes he reached for his red card yet again to send off Barnsley's Antony Kay for what was a very poor off the ball challenge.
Doncaster made sure of the points seven minutes from time thanks to a great strike from former Barnsley man Dave Mulligan.