score:8
Speaking from experience (2 double-entry visas for me, and a few multi-entry visas for someone else), there's definitely both an entry and an exit stamp for each entry.
Of course, there can always be exceptions - I don't think passport stamps are ever 100% reliable - some border agents may not know all the rules, etc. Some border crossings can be really strange - e.g. land border between Kyrgyzstan and China - it's really easy to miss a stamp there.
Did the Chinese consulate ask you for a scan of your previous Chinese visas or did they also ask for entry/exit stamps? If it's the former, chances are they're just going to look up your information by the visa number in some database (but I'm just guessing here).
Upvote:5
Looking at my passport, I can assure you that the standard is to stamp on each entry and on each exit - on the first empty page of the passport, not (necessarily) on the opposite page of the visa. Since multiple entry visa can last a year, and you might travel to other countries between your first and last visit on the visa, there might be other stamps and stickers beyond the page of the China Visa.
Also, the page opposite of the China visa might be used by other immigration officers. On one of my pages opposite the China visa I can find Phillipine and Taiwan stamps. On the following pages then multiple Chinese stamps.