Overlapping Notes in Step Sequencer

I'm using drum maps in Sonar X1d 64bit along with battery 3, and the step sequencer.  After programming my drums, I noticed that the step sequencer will trigger doubles of the same sound.  For instance, after I layout a series of kick drums and hit play, the kick has this doubled flanging sound. Then when I remove the triggered kick from the step sequencer, I can still hear it but without the flanging sound.  Has anyone else experienced this?  Any feedback would be deeply appreciated.