Hello,
In JUNOS, lo0.<unit> defaults to LAN interface type for OSPF.
Configure p2p OSPF interface type and you won't see DR on lo0.<unit>:
set protocols ospf area <area#> interface lo0.<unit> interface-type p2p
Also it's a good idea to configure lo0.<unit> as "passive" under OSPF.
HTH
Rgds
Alex