There isn't really a way. If you write, say, SCP-3969 (totally random number) and have two offshoot scips from that, you have to call them SCP-3969-1/A and SCP-3969-2/B. Sometimes people do change it to things like 'from now on, referred to as 'the subject', but that can be a bit hit and miss, and depends on the strength of the article already, since you're not supposed to give casual names to your SCP items. You can occasionally also just say -1/A or -2/B when describing something, for example -
'Unlike SCP-3969-1, -2 displays effects that are more…'
But really, even if it bores you as an author or as a reader, the proper way to refer to them is always the best way to go. If you're finding you're writing it a lot, you're probably using the terms too much when you could write things in another way.
