Should I use "multiple" and "at once" in one sentence?
Solution 1:
It seems that there's nothing wrong in this phrase, as long as "multiple" refers to the noun "services".
Solution 2:
At once has at least two different, but related meanings
1 at the same time : simultaneously
2 immediately
While your usage may be comfortable with both, there could be circumstances where the immediately may be understood, but where you wanted to focus on at the same time.