Shouldn't be a problem in that case. If you were using a Tape unit, then issues would have arose.
Though always preferable not to run multiple backup applications on the same machine. There can be be port conflicts, performance issues, VSS issues etc.
If the host isn't being backed up, then VSS conflicts can be ruled out.
I guess you'll have to ensure no ports are common between BE & DPM and secondly, there may be disk performance issues