URL redirect to multiple paths

I haven't worked much with policies but iRule should be able to help you out. If you are looking to redirect, you should be able to use something like this:

when HTTP_REQUEST {
if { ([HTTP::host] eq "example.123.com") } {
if { ([HTTP::uri] eq "/") or ([HTTP::uri] eq "/loginpage2") } {
HTTP::respond 301 Location "https://example.123.com/loginpage1"
}
}
}

If you are just looking to replace the URI and send it directly to server instead of a redirect:

when HTTP_REQUEST {
if { ([HTTP::host] eq "example.123.com") } {
if { ([HTTP::uri] eq "/") or ([HTTP::uri] eq "/loginpage2") } {
HTTP::uri /loginpage1
}
}
}