As far as I can remember, there was ONE throwaway line about their differing last names, concerning their family situation being complicated. Other than that, though, we don’t have any concrete answer. I imagine the name is likely from Sithe’s husband (ex-husband? deceased husband??? who knows).

Luckily the ending I’m talking about has been translated. I can share the link with you =).

Hello~ (I had a great vacation!)

With the exception of Joker, who is a non-individual existence, all the other role holders are hours of time while the faceless are all minutes and seconds. It’s unclear what hour each character embodies. In Peter’s case we know he is part of the afternoon, and 3 o’clock seems to come up again and again in relation to him. He is probably the easiest to guess. We also hear from Nightmare that he must keep one eye closed at all times because of his role, but it’s unclear if that has to do with what hour he is or if there is another reason.

There is a slight chance that Nightmare named the role holders by order of hour in the true end. I can’t say for certain but Peter is in the proper place if that is the case.

キング、女王、白ウサギ、エース、時計屋、三月ウサギ、帽子屋、双子の門番、チェシャ猫、ゴーランド、そして私だ。 (Translation: The King, the Queen, the White Rabbit, Ace, the Clock Maker, the March Hare, the Hatter, the Gatekeeper Twins, the Cheshire Cat, Gowland, and I.)

So that would be:

1 o’clock - King

2 o’clock - Vivaldi

3 o’clock - Peter White

4 o’clock - Ace

5 o’clock - Julius Monrey

6 o’clock - Elliot March

7 o’clock - Blood Dupre

8 o’clock - Dee/Dum (Not sure which is which. My instinct is to say Dee and then Dum.)

9 o’clock - Dee/Dum

10 o’clock - Boris Airay

11 o’clock - Mary Gowland

12 o’clock - Nightmare Gottschalk

If this is true then Gray and Pierce would most likely be the replacement for 5 & 11 o’clock in Clover.