Georgi,
I think this question would need some clarification, and it depends on whether the two routers are the ONLY routers that are neighbors, or whether there are more than two routers.
The situation you describe could happen where the router that is in 2-Way has not been elected as a DR or BDR. In this situation (assuming we are dealing with a multi-access network), this is perfectly normal to have a 2-Way state. Any router that is not a DR or BDR that has a neighbor relationship with another router that is also not a DR or BDR would show up as 2-Way/DROTHER.
Now, if the person asking you this question was talking about where the two routers’ relationship with each other, that is a different story. In other words, let’s say there are two routers: A and B. If you issue “show ip ospf neighbor” on both A and B, and A shows as Full with B, but B shows as 2-Way with A, I don’t have an answer for that situation. In multi-access networks, OSPF only forms a Full relationship with either a DR or BDR, and that Full relationship goes both ways, so in this case A and B should see a Full relationship with each other. If only one side is seeing Full but the other is 2-Way, something is wrong, but I can’t think of what would cause that to happen.
Do you know whether there were only two routers in the scenario presented to you?