It did not split on Amethyst.
It sent one one invoice, half, to a single individual. It did not to a second for the remainder.
Discussion
That is probably your NWC then cus I did it on amethyst and it worked.
Which wallet are you using?
Minibits.
Does it show that the other payment failed in nostr:nprofile1qqstxwlea9ah3u6kjjszu6a7lrnhqkfh8eptp2z6v0e9558tlkkl2rgpz4mhxue69uhhyetvv9ujuerpd46hxtnfduhszxnhwden5te0wfjkccte9ekkjmnfvf5hguewvdshx6p0qythwumn8ghj7un9d3shjtnswf5k6ctv9ehx2ap0wsvavr
There was no other payment.