I don't see it as fraud.

The OP gave the receipt for the actual price of the laptop to the claims adjuster.
The claims adjuster choose to pay out the greater amount, for whatever reason.

If you had claimed the laptop cost you 1000 when it only cost 600, that would be fraud.
Having given them the correct information, and the insurance company choosing to give you more is not fraud.
I'm not sure if the adjuster's supervisor would be terribly happy, but even if they made an error, the OP did not lie/cheat/steal or commit fraud.