When was disassembling the engine (somewhat), there was the upper dipstick tube which presses into the opening, but below that there was another metal sleeve which sat at the BOTTOM of the dipstick tube hole in the block. This tube sticks a few inches into the pan past the block below.

Is this normal? What is the purpose of this lower dipstick tube "sleeve"? Can I just not use it?

I'm just wondering what the heck it's for and do I need it.