I know that ラルク is the band L'arc En Ciel. What does コピー mean here? What does the first sentence say?
コピー 'copy' in this context means to play a song of a band in the format as close as possible to the original. Often, you reconstruct the music score by listening to that song. If it is done in this way, it is particularly called
耳コピー 'copying by ear'.
じゃあ最後にもう一度聴いてくれ ... 虹。 means 'Then, please listen again. This will be the last song Niji.'
A conversation wouldn't flow that way, at all. I'm positive. Is there more context? ってやってた is very poor Japanese. It's something that would not be said on a tape or on in an instructional book. This is what A-san would say: 何からその情報を得たのか. It's because って doesn't belong and やってた would mean that you're speaking down to the listener, as if the listener is a mangy dog or a very very low subordinate who warrants no respect at all. Nobody is so rude, except for a rowdy high school student, especially not in writing. Even in the case of high school students, they are usually insincere with this kind of jarring.
Copy isn't used properly here. So, it doesn't have any meaning. Copy has no meaning in this sentence. While it's true that 耳コピー has a meaning: 'copy by ear', it is very rarely used, even when asking for such a thing. Also, I am here with a friend of mine, and neither of us can think of any other case where a word directly proceeds コピー. There's always a particle between two words where the second word is コピー, with only the exception of the word 耳コピー.
Here's the question Native Japanese speakers will ask themselves when they read this sentence:
どういう状況でコピーを使ったのか？-> What is it a copy of?
It seems the only (extremely unlikely) possibility is that the speaker is saying: "Is it a L'arc En Ciel copy band?" There's an even less likely possibility that they're saying: "Is it a copy of L'arc En Ciel's song?" If that were the case, the speaker would definitely say ラリクのコピーバンドですか or ラリクの歌をコピーしましたか. In either case, 他にも would cease to have any place in the sentence. 他にも would sound equally as strange and out of place in one of these corrected versions as ラリクコピー sounds in the original sentence.
So, isn't it possible that you misheard what was said? That seems most likely.