Miltiple Ajax post call

Miltiple Ajax post call

I have been tried for whole day and still can't find a solution to my jquery multiple post request problem.

When I fast click Button-A then Button-B to trigger ajax call, the result on success: $(ID).append(data) completely goes wrongly into different target ID.

I tried set async:false but it is deprecated. I'm using jquery ver 1.11.2.

Thank you in advance for any help.