Is it normal to be really annoyed by people who talk over you?

Oh yes it annoys me a lot, the contradiction being that I do it myself.

I really hate it when it happens so if someone talks over me when I'm trying to help them then I let them and don't even attempt to give them the information they need.

Happened trying to get a new dresser into a bedroom and I tried to say twice the way they were doing it will break it but got cut off by both twice so I just shut up and let 'em do it how they wanted and as expected it broke. When it got brought up later I said I knew it was going to break and they say why didn't I bring it up to which I just said that I did twice and you didn't listen, and now you have a broken dresser.

Now when anything similar happens with the two people I'm talking about and they cut me off to only then after say, "Sorry what were you saying?" I just reply "Doesn't matter" and they freak the fuck out because they don't want a repeat. I'd be lying if I said I don't get some fun out of it now.

You defeat people who interrupt people by interrupting them.

Yes, I used to be that very soft spoken, shy person and would pretty much just sit there the entire time watching everyone else talk, then people would assume I was unfriendly because I "never talked". Lol, I tried, but you guys wouldn't let me have a single word in edgewise!

if someone did that for me I'd be really touched, I'm hella anxious around people I don't know well.

Not so with people I'm familiar with though and I call out my mom often because she regularly interrupts me and my dad talking. We're in a conversation and she'll just interject (in the middle of someone else's sentence) with something totally unrelated. and I'll say something like "Um?? We were talking about [xyz], actually. Does what you just said have anything to do with that?? Is it more important than our conversation??? Could you have at least let us even finish our thought or said excuse me!"

It's the worst because I can't do the "keep talking over them" trick since I completely lose my train of thought when she starts talking (ADHD, easily distracted).

Personally if someone's talking and I want to say something (presuming it's either someone I'm comfortable with or needing to say something important), then I'll kind of start with saying some variation of "um", or the first couple words of a thought ("Yeah, I-", "Oh, and-", etc). This lets them know I have something to say, and with most people they'll either stop talking and say "yeah go on?" or they'll finish their thought quickly and ask "and what were you going to say...?".

I guess if they keep talking for a long while even after I've made multiple indications of wanting to speak, I'll either shrug it off or go quiet but look very clearly disgruntled/annoyed.

Go to some of the museums in London and show them the naggers scolds of yesteryear!

I deal with this all the time with my wife. She’s a bit of a motormouth. Assuming she pauses enough to get a breath, I’ll ask, “Are you done?”

When someone does that I make sure I finish my sentence even if we both talk at the same time. Never stop your sentence. Get louder as they try to talk over you too. This will show them that you arent going to be spoken over. I think its just rude. I always try to let people speak and include everyone.

talking over someone shows disrespect and is wrong

Yeah i'm soft spoken and have social anxiety and it happens a lot. I dont really think people mean to be rude though, some are just really loud and can never shut up even for 1 second... Would be nice though if such people were ever told to be quiet and look outside themselves, like all quiet people constantly get told to speak up and be tougher etc.