That's odd, is that an Android phone? On mine you are simply not able to do it. Makes sense to me, as you could then send that screen shot to literally anyone for them to use, which is obvs not what's intended. Sorry if I'm missing something here, perhaps it's different for Season tickets than...
You do need to be careful to just do one of them. Then your friend can do the other, they will need to be careful do the other one. A bit fiddly, but as long as you stick to that it will work. No worry by the way 😀
Sounds like you've bought him a guest ticket? Assuming the e-mail had two links on it, you can forward the e-mail as long as you make it clear which one your friend needs to download.