Can i re-enter US with my existing L1B blanket visa if my new L1B blanket is rejected

[Vico]

I am currently on L1B visa expiring on April 4th 2019 (I-129S is till April 2019, PED on stamping is till 27th April 2019 and Visa expiry date is 27th April 2021). I have applied for extension and i was asked to go to Canada for L1B Blanket interview and stamping. I have booked the appointment for February 1st 2019. Question is - If my interview did not go well and if it gets rejected will i be able to re-enter US with my current Visa validity (more than 8 weeks)? Will the VO cancel my existing visa stamp (under "Cancellation without prejudice" clause as i am apply for a visa under the same category) also during the interview and in this case i will be out of status after the interview and will be stranded in Ottawa without any backup plan.

[Libra_14]

I am currently on L1B visa expiring on April 4th 2019 (I-129S is till April 2019, PED on stamping is till 27th April 2019 and Visa expiry date is 27th April 2021). I have applied for extension and i was asked to go to Canada for L1B Blanket interview and stamping.

Who asked you to go for stamping again? You already have a valid visa till Apr 2021?

I have booked the appointment for February 1st 2019. Question is - If my interview did not go well and if it gets rejected will i be able to re-enter US with my current Visa validity (more than 8 weeks)? Will the VO cancel my existing visa stamp (under "Cancellation without prejudice" clause as i am apply for a visa under the same category) also during the interview and in this case i will be out of status after the interview and will be stranded in Ottawa without any backup plan.

It depends on the VO - at times they cancel existing visa as well. But if he doesn't, then you can surely re-enter with your existing valid visa & most probably you'll get I94 same as your petition expiry date.