Why does adding zero change the result on wolframalpha? (i.e. A*B != A*B+0)

Question

exhibit A

[[-V,0],[U,0]]*inv([[1,0],[-rho,1]])*[[-1,0],[0,Y]]

=

[[V,0],[-U,0]]

exhibit B

[[-V,0],[U,0]]*inv([[1,0],[-rho,1]])*[[-1,0],[0,Y]] + [[0,0],[0,0]]

=

[[V,0],[0,0]]

but

[[V,0],[-U,0]] != [[V,0],[0,0]]

What gives?