How to set OSPF dummy0 propagation cost?

Hello, I have a simple question for most of you, .... I have Bird 2.0.7 and using multiple dummy interface (lo0 and lo1) with /32 IP address. I can propagate this interface using # R1 with lo1: interface "lo1" { cost 2000; stub; }; # R2 with lo1: interface "lo1" { cost 10; stub; }; #router 3 get the same cost for /32 route from R1 and R2 question is - how to propagate the lo1 address from multiple devices with the different costs? Attribute "cost" not makes any changes. What I miss? Thank you. Regards Petr B.