I've got this document in its .PDF form from the French Service Historique de la Défense. It is dated 18th of June, 1945 and states that one Maus, built in October, 1944 was sent to Berlin, and two were sent to Kummersdorf (my italics).
It is in French, I'll translate it for you:
CONCERNING: German tank Pz.Kpfw "MOUSE"
1.- The search by Team Number 7 for the "MOUSE" at Böblingen (Germany) was fruitless, however interrogating Karl FROHLICH, Director at the Böblingen complex has revealed that:
1- The tank was built at Stuttgart in 1944
2- A specimen was put together at Stuttgart in October, 1944
3- Specimen was sent to Army Museum in Berlin
4- Hull was built by Krupp
5- Powerplant was an 1000 HP Daimler-Benz aviation engine
6- Transmission built by Z.F. in Friedrichshafen
7- Electric equipment was from Siemens in Berlin
8- Radio equipment was from Telefunken
9- Miscellaneous equipment was built by F.A. Telekin
10- A wooden model was at Krupp, Essen
11- Assembly was made by F.A. Alkett in Berlin
12- Two models were sent to Böblingen
13- New engines were installed at Böblingen
14- The models were then sent by rail to Berlin Wimsdorf or Kummersdorf
2.- All the plans for the "Mouse" were taken by two British Officers prior to Team 7's visit.
No "Mouse" type vehicle currently exists at Böblingen.
Signed, Josset [...]
Here it is in facsimile: