After a bit of investigation I found reference to an exhibition held at Rechlin around the time you specified, Capt Vick. In German Secret Flight Test Centres to 1945 (got it!) it states that on 12th and 13 June 1944 all the LW E-Stellen displayed the latest German equipment, such as He 177B-5, Ju 88S-3, Ta 154, He 219, Fw 190, Ar 232B, Do 335, Ar 234, Me 262 and Me 163, as well as the latest beute Allied aircraft. Listed in the book is the following; Fortress, Liberator, Lightning, Mustang, Spitfire, Mosquito and Typhoon, but no mention of a Lancaster, but Lerche's Flugbuch certainly confirms he flew one there beforehand, so it can be assumed (with some hesitation) that it was there. Here's a comment from the book.
"Participants at the inspection noticed immediately the difference between the superb and matching construction components of the American aircraft in comparison to the very imperfect manufacture of the German aircraft,as noted in a report compiled by Flugbaumeister Kroger of the Arado firm."