The sad but predictable consequence of making memo free to post is the return of spammers, racists, nazis, qtards and other shitheads that can't wait to waste other people's satoshis on their bullshit
Blockchain.com continues to give $25 of free Stellar XLM tokens for free. This is not some scam shitcoin Airdrop. All you have to do is sign up and verfy your account. https://www.blockchain.com/getcrypto/claim
Yes they are different, once the unsplit coins run out, all messages will be different. Now some of them are broadcast on both chains , because unsplit coins are used.
Memo identify a message by its transaction ID. If a message have same transaction ID on both BCH & BSV chains, these 2 messages can be considered same, which requires unsplitted coins.