This may give an economy fingering so that also provides a smooth connection
for continuous notes.
Let us check MB fingering for this phrase at YouTube.
I happened to find the scene of the phrase with a movie close-up MB's hand.
All I could see was MB's left hand, but right hand position might be supposed.
See fig. below.
By the video,
MB plays double-"B(A on C.T.)" with 2 other alternate fingerings
(without using a normal fingering).
For me, this is an annoying "truth".
I do not have an ease to pronunce this B(3rd note) by E finger form on
I have no way but to use current fingering.