Fourteenth Doctor's bi-generation

Can someone tell me, what the hell is going on?the Fifteenth Doctor, shortly after being generated

Fourteenth Doctor's bigeneration
First appearance:	The Giggle
Dates:	November 2023
Location:	UNIT HQ, City of London
Result
The Fourteenth Doctor splits into himself and the Fifteenth Doctor
← Previous	Thirteenth Doctor's regeneration

The Doctor's regenerations
Timeless regeneration cycle
First Doctor's regeneration cycle
New regeneration cycle
Other regenerations

About the Doctor

History

Cause

Whilst confronting The Toymaker, the Fourteenth Doctor challenged him to a game, the third they had played overall. However, as both of their games up to that point had been played by different incarnations, the first game by the First Doctor, and their second by the Fourteenth Doctor, The Toymaker declared that the next game must be played, by the Next Doctor and shot him through the chest with a Galvanic Cannon, causing him to begin to regenerate.

Two Doctors

However, instead of changing appearances as usual, the Fourteenth Doctor recognized that something was different and asked Donna Noble and Melanie Bush to pull on his arms, causing him to begin to separate into two distinct incarnations of the Doctor, to the confusion of all present. The Two Doctors greet each other excitedly before pushing against each other to complete their separation.

Aftermath

Now seperated, both Doctors challenged the Toymaker to their final game, which they won, with the Fourteenth Doctor banishing The Toymaker from N-Space as his reward, while as his prize, the Fifteenth Doctor created a second copy of their TARDIS, so that he could continue adventuring while the Fourteenth Doctor could retire to heal from lifetimes of loss and battle.