Hi Priti
these are occational issues which happen in the system due to multiple database updates
You will find issues like extra GR or invoice or others in the PO, similar to your issue.
IF i am guessing it right, both GI would be posted with less than 15 minutes interval. the first one got posted, however, the insert queue of the database didnot clear the record and second time again it got posted. These are issues which even SAP doesnot answer (as they are non replicable), i had raised an OSS myself before
Here, to solve this, you have to temporarily increase the stock and delete the extra or both GI and perform the cycle again.
Please let me know in case your issue is solved with this
Regards
Vivek Singh