You seem to be confusing two different things.
A "backdoor Roth" is making a non-deductible contribution to a Traditional IRA and then converting that to a Roth IRA so that the non-deductible contribution offsets the tax on the conversion. That only works if you has no traditional IRA account whatsoever before the contribution and ended up with no Traditional IRA account after the conversion.
Rolling and converting a 401(k) to a Roth IRA has noting to do with a backdoor Roth. Yes, if you specify that the 401(k) is to be converted to a Roth IRA then it can be done directly without first going into a Traditional IRA account. The 1099-R for a direct conversion should have a code G in box 7 and box 1 and 2a both with the amount converted so that the entire amount will be taxable.
If you also make a non-deductible Traditional IRA contribution and converted that to a Roth (backdoor Roth) then you will receive a separate 1099-R for that Traditional IRA distribution.
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**
