Is it permissible to pray Dhuhr shortened, then pray Asr shortened behind the same Imam who is leading Asr, with a difference in intention between the Imam and the worshipper in the first two rak'ahs (with the intention of Dhuhr), then to separate and rejoin the congregation again with the intention of Asr?

Some scholars have permitted a person praying Dhuhr to follow an Imam praying Asr, but it is better not to do so. If a traveler prays behind a resident, he must complete the prayer; otherwise, his prayer is invalid. This is similar to someone who prays two rak'ahs for Dhuhr and four for Asr; in such a case, he must repeat both prayers.