This is interesting.
When we buy from the mall with a "buy" command (which is what I assume you did; you did not say how you generated the result you did include), we first search the mall with a "maximumResults" parameter of 10. If you have already bought your limit of 10 stores, that's all you get.
The Mall Purchase frame has the same issue; if you say that you want 10 results but have already bought out the first 10 limited stores, you see nothing new.
This is definitely a problem for the "buy" command; if you say "buy 100 x", it should search Y at a time, buy as many as it can - and search again, Y at a time, skipping over the already-limited stores, to, eventually, buy the 100 items you said you wanted.
The Mall Purchase Frame is not automated - but if I want to show the next 10 stores which will sell to me, I'd like it to filter out the stores that I have already bought the limit from.
I approve the fix for this for both cases. Whoever does it. Which might be me. Or not.