L1 is pending with RFE and H1B got approved.

My L1B visa got expired on 18-JUN-2013 and also I-94 expired on same date. Before expire of my VISA,  my employer applied for (L1B to L1A conversion) extension and I got RFE with return date as 16-SEP-2013.  Now my employer don't want to return RFE as some policy change at organization level.  

I have approved H1B ( with different employer) which start date as  01-OCT-2013. Any legal issues if I stay 14 days in USA between 16-SEP-2013 to 30-SEP-2013 ?

Was the H-1 approved w/ COS?

Yes it is w/ COS. My H1 approved in May 1st week with premium processing, before my L1B I-94 expired. Will wait for your valuable suggestion

Legally, your valid status in US ends w/ RFE return date, and you should no longer stay beyond that date.

14 days may or may not be a big issue in the long run. Your attorney can guide you if it can cause issue in the long run.

Another option is to file COS to another visa status for those days. Do you have a spouse on a visa other than L-2?

Unfortunately No. Thanks a lot for your suggestion, i will try to find with attorney!!