On separate occasions, they both advised her to stay away from Hamlet because he would only hurt her.
They both urged her to pursue a relationship with Hamlet in order to increase their social standing.
Their advice clashed: Laertes was friends with Hamlet and encouraged Ophelia to spend time with him, but Polonius did not trust Hamlet and told Ophelia not to believe anything he said.
They gave her opposite advice: Laertes had an old grudge against Hamlet and told Ophelia that he was not worth her time. Polonius, however wanted Ophelia to continue her relationship with Hamlet because they were friends.