Each half plug piggy-backs onto the next. The end of the bus is terminated with a resistor plug that itself piggy-backs onto the end of the bus.
Although manufactured in year 2000 this is a very old card design of AXE10 BYB202 more reminiscent of the 80s.
Function: Subscriber Line Test.
Product code: ROF 137 1533/1 R2C
Manufacture date: 2000 Week 37.
Card name: LCT (its actually on the card as LTC)