Those are two separate piles. A double close is two sales: the original seller to you (people call it the A-B leg) and you to your end buyer (the B-C leg). Transactional funding pays for the A-B leg only, and it gets repaid out of the B-C proceeds, usually in the same session. The flat fee you were quoted is the price of that money and nothing else.
On top of it you're closing twice, so you pay settlement fees twice, recording fees twice, and in states that charge transfer or deed tax you may pay it on both deeds. Some states charge on each transfer, some don't tax at all, so this one is worth pricing in your county specifically before you commit to a spread. You'll also usually buy an owner's policy on the A-B leg and your buyer buys one on the B-C leg. Many title companies have a short-term or back-to-back rate that discounts the second policy when the deeds are minutes apart, and it's worth asking for that by name.
The piece neither funder mentioned: the fee is flat, so it doesn't shrink because the money was only out for two hours, and it doesn't stay flat if the B-C leg slips. Ask what happens if your buyer funds tomorrow instead of today. Some funders charge a per-diem, some charge a second full fee, some just take the property. Get that answer in writing along with the fee itself.
