Brass Knuckles
Artifact — Equipment
When you cast this spell, copy it. (The copy becomes a token.)
Equipped creature has double strike as long as two or more Equipment are attached to it.
Equip 
(: Attach to target creature you control. Equip only as a sorcery.)
Yeong-Hao Han
Commander Masters (CMM)
• #372Rulings
A copy of a permanent spell enters the battlefield as a token. This is not the same as an effect that creates a token, and any effect that refers to creating a token does not apply to copies of permanent spells.
(wotc • 2022-04-29)
Multiple instances of double strike do not increase the number of strikes. That creature still only gets to deal combat damage twice.
(wotc • 2022-04-29)
Rulings
A copy of a permanent spell enters the battlefield as a token. This is not the same as an effect that creates a token, and any effect that refers to creating a token does not apply to copies of permanent spells.
(wotc • 2022-04-29)
Multiple instances of double strike do not increase the number of strikes. That creature still only gets to deal combat damage twice.
(wotc • 2022-04-29)