I know about the Iridum-33 and Kosmos-2251 collision, but has there been any collision between active spacecrafts? Any claim regarding the same?
Progress M-34 collided with Mir in 1997. Caused a leak in a module.
DART, or Demonstration for Autonomous Rendezvous Technology, had a low speed collision with MUBLCOM arising from a problematic autonomous rendezvous manoeuvre. The following details are only from Wiki
The two satellites were launched separately. Both were US owned satellites, MUBLCOM being owned by DARPA, DART by NASA. The collision apparently occurred at about 1.5 m/s ( ~ 3 miles per hour), DART had a mass of 360kg and MUBLCOM about 50kg and the satellites both apparebtly survived the event without damage though other factors lead to the rendezvous manoeuvres being abandoned.