One occurrence can bear two different relations. Khalq (creation) concerns bringing an act into existence; kasb (acquisition) concerns its occurrence through the person's intention, choice, and relevant capacity.
Consider deliberately writing a statement. The person intends the act, moves a pen, and is accountable for the words. The occurrence of the act remains under divine creation; nevertheless, attributing the act of writing to the human agent is meaningful and real.
The distinction does not establish two independent creators. God creates, while the servant acquires. It aims to preserve both divine creative sovereignty and human accountability.