Does commander damage from a copy of your commander count toward the 21 damage limit?

Under the Commander format rules, a player loses the game if they have been dealt 21 or more combat damage by a single commander over the course of the game. The key question is whether the copy in question is actually a commander.

A token copy of a commander (for example, created by a card like Delina, Wild Mage or Strionic Resonator copying a triggered ability) is not a commander. Tokens are never commanders (CR 706.10), so combat damage dealt by a token copy does not count toward the 21-damage limit.

However, if your commander itself is copied in the sense that its characteristics are being used by another permanent that somehow retains the commander designation, that would count. More relevantly, if you use something like Sakashima of a Thousand Faces as a second commander, it is its own commander and tracks its own separate 21-damage total — it does not share a total with the original.

Concrete example: Your commander is Krenko, Mob Boss. Delina attacks and her trigger creates a token copy of Krenko. That token copy deals 3 combat damage to an opponent. Since the token is not a commander, those 3 points do not count toward anyone's commander damage total. Only the real Krenko's combat damage is tracked.

In summary: damage counts only if the permanent dealing it is actually designated as a commander. Token copies, spell copies, and similar non-permanent copies are never commanders and never contribute to the 21-damage threshold (CR 706.10, Commander Rules Rule 10).