Looking for device that help me split a n bit input bus, or n analog lines into two or more bus at output
A couple ideas:


Use two n-bit wide tri-state buffer devices.  Tie one of your control bits to the enable input of each buffer.  As an example, you could implement a 4 bit wide version of this circuit on a single 74LS240 chip.  Since the enable inputs are often active low, you may need to invert you control signals.  If you want the outputs to be in a certain state when inactive, add pull-up or pull-down resistors at the outputs.
This would be pretty simple to implement on a CPLD.  If you have the tools to do that, in my opinion, it would be a simpler solution than using an MCU.
As you mention, you could implement with an MCU, using DIO pins to check the inputs and drive the outputs.