Weird behavior with multiple pool inside shared networks on isc-dhcp-server

Question

I have a weird behavior on my dhcp-server, I am using a load balance configuration and using multiple pool inside that shared-network, I have this configuration:

shared-network "my-shared-network" {
    subnet 186.88.128.0 netmask 255.255.224.0 {
        option subnet-mask 255.255.224.0;
        option routers 186.88.128.1;
        pool {
            range 186.88.128.2 186.88.159.254;
            failover peer "my-failover";
        }
    }
    subnet 186.90.0.0 netmask 255.255.224.0 {
        option subnet-mask 255.255.224.0;
        option routers 186.90.0.1;
        pool {
            range 186.90.0.2 186.90.31.254;
            failover peer "my-failover";
        }
    }
}

Works fine for subnet 186.88.128.0, but when I receive packages from subnet 186.90.0.0 my servers offers IP from subnet 186.88.128.0, what I see on logs:

Oct 26 18:22:09 my-server dhcpd: DHCPDISCOVER from 60:e7:01:4d:f9:3f via 186.90.0.1
Oct 26 18:22:09 my-server dhcpd: DHCPOFFER on 186.88.139.127 to 60:e7:01:4d:f9:3f via 186.90.0.1
Oct 26 18:22:09 my-server dhcpd: DHCPRELEASE of 186.88.139.127 from 60:e7:01:4d:f9:3f via 186.90.0.1 (found)

What is wrong with my configuration?

P.D: All DHCPDISCOVER comes from the same IP, for example: 172.16.25.40

Thanks in advance