Hi there,
I've just made a new melody which i really like, but i'm afraid that can be similar to another melody that i don't know.
Have you ever had this feeling ? if so how can you be sure that is a unique melody?
Thanks

 

Yes, and I think it is rather normal (at some point).

You can't. There might have always been some Chinese guy who whistled that exact melody while walking somewhere in the mountains back in 1486
If your melody is obscure or really complex, the chances are of course a lot lower, but you can never be 100% sure that the melody is unique.

But that isn't really a problem. There are many songs with the same or a similar melody and/or rhythm, but most of the time they have different genres/styles/bpm/etc. so it doesn't matter that much.
Yes, there might always be the chance that you subliminally heard that melody somewhere and can't remember, but you just have to accept that.
This problem is something you can't really affect so you don't need to worry about it.

(well if you produce some kind of mainstream electro and your melody consist of 4 different notes, then chances might be a bit higher that it will resemble other melodies )

A example would be the "Gemini - Blue" chorus that (in my opinion) sounds like the "BT - Suddenly" chorus (just a different key) and no one really cares. (there are probably better examples but I can't think of one atm)
Gemini - Blue: https://youtu.be/tcWzVUlrzdc?t=1m20s
BT - Suddenly: https://youtu.be/NDPx9micphM?t=1m6s

 

Similar melodies/chords/arrangement... are more a personal matter than law one.
If you like something, use it. May be some ppl will raise a question. But almost all ppl will not care about similarities.
In fact, 90% of the music we are listening to is just the same for decades, with new clothes
Don't fear anything.

Sampling is another story

 

yeah i'm hearing ya.
it really sux cos you want your work to be original because it's yours. you're invested and proud of it.

if it bothers you enough, scrap it. but as the others have said, just go with the flow especially if it's good.

also, is it possible you're recognising it because you've used it yourself and not followed through with it before?
i found I had this one motif kept popping up in my work cos it fit my style and taste so perfectly.