B0Unique is an option of B0. If set to True, B0[0,0,m2] is replaced with (B0[0,m2,m2]+1) and B0[m2,0,m2] simplifies to (B0[0,m2,m2]+2).
By default no transformation is done.
B0[0, 0, s]\text{B}_0(0,0,s)
With B0Real->True following transformation is applied
B0[0, 0, s, B0Unique -> True]\text{B}_0(0,s,s)+1