John Gill Commentary Genesis 43:12

"and take double money in your hand; and the money that was returned in the mouth of your sacks carry again in your hand; peradventure it was an oversight:" — Genesis 43:12 (ASV)

And take double money in your hand Than what they carried before, either to buy as much more as they then did; or rather because of the greater scarcity of corn, as Jarchi observes, which made it doubly dearer; for this seems to be different from the money they are also bid to take in return for that found in their sacks, which was a third parcel, as follows:

and the money that was brought again in the mouth of your sacks, carry [it] again in your hand; that it might be ready to pay upon demand, should they be charged with nonpayment for the corn they had before:

perhaps it [was] an oversight; a mistake of the governors, or of those that were under him, concerned in the sale of the corn, and receiving money for it, or of Jacob's sons; he could not tell how it was, but some way or other he supposed a mistake was made.