It *is* a bit ambiguous. I have always treated "different sample preps" under "intermediate precision" per ICH, but I could see it included in "repeatability" if all run on the same day. As long as you document what you *actually* did, you should be Ok.
Here are the definitions:
a. Repeatability
Repeatability expresses the precision under the same operating
conditions over a short interval of time. Repeatability is also termed
intra-assay precision
b. Intermediate precision
Intermediate precision expresses within laboratories variations: different
days different analysts, different equipment, etc.
c. Reproducibility
Reproducibility expresses the precision between laboratories
(collaborative studies usually applied to standardization of methodology).
per:
https://www.fda.gov/media/71724/downloadMy rationale is that "single prep / repeat injections" establishes the performance of the *chromatography*, including injection volume, but also detector response, integration settings, etc. "multiple prep / repeat injections incorporates the performance of the entire method, including the chromatography and sample prep.