this sounds very strange and I'm pretty sure that it doesn't behave like you think it behaves.
How would the second process even know when the "second" word from possibilities.txt begins. It has no information about the words. The second command only runs everything it get's as input.
I think there are many ways to troubleshoot this. e.g. using a "cat" or "type" command as the first part of your pipe, instead of the stdout command.
you should also test with the newest beta version of hashcat from https://hashcat.net/beta just to make sure and probably also test older versions from https://hashcat.net/hashcat
you should also look carefully at your status prompt (hashcat output). maybe you have a lot of rejected password candidates (there is a line for that too)?
How would the second process even know when the "second" word from possibilities.txt begins. It has no information about the words. The second command only runs everything it get's as input.
I think there are many ways to troubleshoot this. e.g. using a "cat" or "type" command as the first part of your pipe, instead of the stdout command.
you should also test with the newest beta version of hashcat from https://hashcat.net/beta just to make sure and probably also test older versions from https://hashcat.net/hashcat
you should also look carefully at your status prompt (hashcat output). maybe you have a lot of rejected password candidates (there is a line for that too)?