In reply to SUNODH:
They are very different.
*rsp_1[2] is a sequence saying that rsp_1 must be true in the current cycle and true in the next cycle.
$stable(rsp_1) is a boolean function returning true if rsp_1 has the same value it had in the previous cycle.
You cannot use the select/condition operator on a sequence. You can use an implication.
property p_rsp_req
@(posedge clk) if (req) rsp_1[*2] else rsp_2[*2];
endproperty : p_rsp_req
Your requirements say nothing about when the 2 clock cycles rsp_1 must be asserted in relation to when req is asserted, or what rsp_1 should be if req is not true