SOME parts of an engineer's work are 2x faster, but not all. Generating code - yes, writing tests and docs - yes, designing the system - no, debugging - no, attending meetings - no, getting your data faster, or moving the other team to finish integration sooner - no help. So it's going to be 10% boost overall, not 100%.

The nice effect is that the AI makes people more confident to try things and go out of their comfort zone. Maybe the quality of the end product will be higher.