[INPUTS NEEDED] Duplicating entries in Posting in MIRO

Good day SD gurus,

I'm currently facing a problem wherein i have duplicate posting upon MIRO execution.

To cut it short - I have successfully posted a document with types:

     RI <-Correct

     RN <-Correct

     RN <-Duplicate ----

Now, I have shallow thoughts on how did my posting produced the DUPLICATES for 'RN'?

I hope someone have inputs on this.

You're response is highly appreciated.

Thanks in Advance.