After they make all the various items for the mishkan, the passuk tells us in 39:42-43 that they did as told. The passuk says, "According to all that the LORD commanded Moses, so the children of Israel did all the work. 43 And Moses saw all the work, and, behold, they had done it; as the LORD had commanded, even so had they done it. And Moses blessed them."
They did the work as Hashem told them, then Moshe saw that they did the work as Hashem had told them and then what Hashem had commanded them to do they had done it.
Why does it have to tell us twice that they did what Hashem said? We got the point already, we need to separate that they did what Hashem said and then have Moshe acknowledge it too?
I would like to suggest and differentiate that the first time it says they had done what Hashem commanded, it was relaying the personal sense of accomplishment. They finished the work and they had done it properly. Something to be proud of!
The second time when it was Moshe seeing they had done according to Hashem's commandments, it is different. Moshe was their supervisor. Their manager. He performed his inspection of their work and found it successful and that they had performed admirably. Not only did he see that they completed their tasks, but he then blessed them.
Moshe was being a good manager. Complimenting those he is responsible for, and motivating them for the future tasks.