This is a better translation of Leviticus 10:1-2:
(Leviticus 10:1-2 NIV) Aaron's sons Nadab and Abihu took their censers, put fire in them and added incense; and they offered unauthorized fire before the LORD, contrary to his command. {2} So fire came out from the presence of the LORD and consumed them, and they died before the LORD.
The other verses are examples of disobedience. Ananias and Sapphira lied about the amount of their offering. There's no such thing as "seed offering". It isn't a biblical concept.
RE: INSTANCES OF STRANGE FIRE