Barclaycard Arrival redemption follow-up

One of the most frustrating things about having multiple rewards-earning credit cards is the fact that each rewards currency is redeemed in a totally different way, and it's not always clear from a card's promotional material what the redemption process consists of. 

That's why last month I walked through a redemption of Barclaycard Arrival World MasterCard miles, so readers could know exactly what they were getting into. But one thing bothered me: in this, the 4th screenshot in that blog post:

There are 4 redemptions options: the last 4 $25 intervals.

I've subsequently redeemed more points using this card, and discovered that when you don't have enough miles to redeem for the full amount of a charge, only three redemption options are available: the last 3 $25 intervals. 

I don't know exactly what the logic behind this is, but my suspicion is that the 4th redemption "slot" is reserved for redeeming miles for the complete value of a purchase. While partial redemptions are only allowed in 2,500 miles, $25 increments, "complete" redemptions are available in 100 mile, $1 increments:

Does this have much of a practical impact? Not really, since Arrival miles are worth 1 cent each, so it doesn't make much of a difference in which combination or order they're redeemed.

Except...the next question I intend to investigate is whether after making a partial redemption it's possible to make another redemption for the remaining amount of the same transaction. Since Barclaycard Arrival World MasterCard redemptions have a 10% rebate of points used to make travel redemptions, It might be possible to redeem 100,000 points for a $1,000 statement credit, then use the 10,000 point rebate to make an additional $100 redemption against the same $1,100 transaction.

Does anyone have any experience making two redemptions against the same transaction?