How to send multiple separate texts to one person at once?

I have an iPhone and often receive multiple, separate, short texts from a friend also on an iPhone that are received almost at the same time (ie, not enough time has elapsed for them to write the first text, send it, write the second, text and then send it).It's as if they've written multiple texts as drafts and then sent them all at once. I've gone back and asked them how they did it and they didn't even know it was happening. Was wondering if there's a way to write/save multiple texts and then send them out at once or if this is just some "glitch" in the system? Maybe there's a delay in receiving the first text so it appears I'm receiving them at the same time?

Evr heard of copy paste, he prob copied it and kept on pasting it and hitting send

Wen writing a text message there are a certain number of letters/ words you can use. When you go past the # of words/ letters it keeps typing but it sends them as 2 different text messages