Help: NIW RFE

Hi,
I submitted NIW application (DIY, without ETA 750B, I forgot) at end of Sept. I got the RFE, which stated "Submit ETA 9089 in duplicate". I know ETA 9089 is for PERM LC, which requires employer's sponsorship. Since DOL has started PERM, ETA 750 is absolete, ETA 9089 is replacing 750. I guess it is the reason USCIS requires the ETA 9089. My question is what I shal1 do now.
1. Just submit the ETA -750B
or
2. Just submit the ETA 9089 without employer's signiture, just fill it as much as I can.
Any comments are appreciated.
BTW, what does "in duplicate" mean? Shall I sign the form twice, or just sign once and ake a copy?
Yun