having problem after recording myself singing

I’m using Windows 8, AUDACITY 2.0.4 version, Recently I recorded myself singing while the AUDACITY software plays at the background the melody.
When I heard the recording I noticed that the melody in the background sounds twice but within a few seconds. How can I fix this?
I need it urgently for a wedding next week.
If you want I can send you the file so you can understand what’s the problem.
please help.

As I recently pointed out to you in your identical posting on Facebook see this tutorial in the Manual: http://manual.audacityteam.org/o/man/tutorial_recording_multi_track_overdubs.html

The point is that once I’ve done this, as I described, and it worked. i didn’t have to do a multi-track Overdubbing in order to make it work. i just removed the vocals and recorded myself singing while the melody was playing in the background.
For some reason now it does not work. Could it be related to room acoustics?

It seems that it has no connection to room acoustics. I tried it in every room in my house and even outside the house and still it doesn’t work. I’ll be glad to send you the file via email.

All that will prove is that your way does not work.
Why not try it in the way described in the manual? Audacity Manual

I do not have all the necessary accessories that are written in this tutorial. Now, do you think i’ll bother myself to buy all these accessories?
there has to be another way to make it work. i know, cause i already did it before but now it doesn’t work.
im asking again, can i send you the file via email?

Did you see the section “Overdubbing using your computer’s on-board sound card”?

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