What does it do? Second Pressure Regulator in Rear brake line

[SJ]

I'm in the process of replacing the rear rubber brake lines at the rear
calipers.
I noticed a second pressure regulator, and dont understand its function.
Maybe one of you techno gear heads can explain what it does.

90 100Q
Rear brake lines.

1. Line from front to Rear Adjustable Pressure Regulator (item 6)
2. Line from Adj Pres Reg to T
3. Line from T-1 to Port side Rear Caliper
4. Line from T-2 to Starboard side to "Brake Pressure Regulator", item 22
5. Line from Brake Pres. Reg. to Starboard side Rear Caliper

I understand the function of the Rear Adjustable Pressure Regulator (item 6,
"Brake Pressure Regulator").  The function is to lower the rear brake
pressure in a hard stop, to prevent rear wheel lockup when the rear wheels
get unloaded.

What is the function of item 22, Brake Pressure Regulator ???
It looks somewhat like the fuel accumulator - one line in, one line out.
Seems that it controls only the Starboard side rear caliper, a time delay of
some sort? For what purpose?

SJ
85 Dodge PU, D-250, 318, auto
85 Audi 4k - - sold but still on the road
88 Audi 5kq
90 Audi 100q