The way this is supposed to work is this.
A trustee-to-trustee transfer of an HSA, where the funds are not paid to you, are neither a distribution nor a rollover and are not to be have been reported on Forms 1099-SA or on Forms 5498-SA.
Because of the one-rollover-per-12-months rule (that is, from an IRA to an HSA), you must get the HSA custodian to correct the form to show that $0 was distributed and $0 was rolled over.
If Bank A's 1099-SA showed anything but $0 in box 1 on the 1099-SA, then you should get a corrected 1099-SA, because this incorrectly makes it appear that this transfer was a contribution.
There is no place to actually report the transfer on form 8889, so it would be fine to just not enter anything for either transfer (the reason for the corrected 1099-SA is to get the HSA custodian send a copy of the corrected 1099-SA to the IRS - you don't particularly need it).
