As I understand in the current runtime implementation of CRT:

• Revenue split and AMM can be active at the same time (nothing in either activate_amm or issue_revenue_split seems to prevent this)
• Users can buy / sell CRT on AMM during an active revenue split (token.ensure_can_modify_supply() is not called inside buy_on_amm / sell_on_amm, even though both those functions affect the token supply)
• The dividend paid to rev. split participants is calculated based on total supply and paid immediately on participate_in_split call

This means that it's possible to claim over 100% of holders' share of a revenue split, ie.:

1. Member A has 100 CRT which is 100% of the current total supply
2. Member A stakes all the tokens on the current revenue split, claiming 100% of holders' share (revenue_split.allocation)
3. Member B buys 100 CRT on AMM and stakes them on the same split
4. Member B claims 50% of revenue_split.allocation JOY, even though 100% of token.revenue_split.allocation has already been claimed
5. Members A and B together have claimed 150% of token.revenue_split.allocation (the amount they can claim is only limited by the balance of CRT module account)