Whether you call it "second work of grace," "third work of grace" or whatever is irrelevant. It's still unscriptural. What you call "entire sanctification" is nothing less than the total obliteration of original sin. This is false doctrine plain and simple. Original sin is never obliterated this side of heaven; we rely on His grace.
'Original sin' is not mentioned in scripture. Did Augustine coin the term?
What teaching do you consider to be false doctrine? The term 'entire sanctification' comes from this verse:
I Thessalonians 5:23
23Now may the God of peace Himself sanctify you completely, and may your entire spirit, soul, and body be kept blameless at the coming of our Lord Jesus Christ.
I have never been to a Pentecostal church where I heard someone preach about being entirely sanctified and never sinning again, though I have heard of such churches. I've even been to churches that had historical roots in the Holiness movement for a few years. I think many of the churches that had roots in the Holiness movement, rather that former Baptists, CMA, etc.
used to emphasize 'entire sanctification', but what that meant varied. The idea of a one-time experience of sanctification after becoming a Christian seems to be a forgotten doctrine in some of these Pentecostal groups. I'm not saying some don't hold to it. It's probably a combination of a lack/absence of scripture to support it and influence from other Christians who don't teach that.
The idea of baptism of the Holy Spirit and additional "works of grace" grew out of the Holiness movement, to which both Parham and Seymour belonged.
Okay, but I think you are interpreting 'grace' in a specific sense that refers to salvation from sin, becoming a Christian, being in right relationship with God.... along those lines. Scripture uses the term to refer to other things as well. Grace is clearly an ongoing thing in the believer's life. I've never though that 'second work of grace' meant a step toward being forgiven from sin and being put in right relationship with God, and I've never heard that preached. I don't even know if I've heard 'second work of grace' from the pulpit. I've just read it in books and online probably.