Its not the habit of Pakistani directors but its the habit of Indians who copy Pakistani material. Some of copied songs and movies of indian from Pakistani film industry are these:

Original song (Pakistani): Larka Badnam huwa from Mr. Charlie
Copied song (Indian): Munni Badnam huwi from Dabang
.
Original song (Pakistani): Kadi te has bol by Naseebo Lal
Copied song (Indian): Kadi te has bol from Love aj kal
.
Original song (Pakistani): Mein Tenu Samjhawan ki by Rahat Fateh Ali Khan
Copied song (Indian): Mein Tenu Samjhawan ki by Arjeet Singh
.
Original song (Pakistani): Channo by Ali Zafar
Copied song (Indian): Chore ki Baatein from Fight Club
.
Original song (Pakistani): Pehle Toh Kabhi Kabhi Gham Tha by Rahim Shah
Copied song (Indian): Pehle Toh Kabhi Kabhi Gham Tha by Altaf Raja

.................................................. .....................................

Original movie story (Pakistani): Aina (1977)
Copied movie story (Indian): Pyar Jhukta Nahin (1985)
.
Original movie story (Pakistani): Taqat Ka Toofan (1989)
Copied movie story (Indian): Khal Nayak (1993)
.
Original movie story (Pakistani): Ghar Pyara Ghar (1968)
Copied movie story (Indian): Hum Aapke Hain Koun (1994)
.
Original movie (Pakistani): Haq Mehar (1985)
Copied movie (Indian): Sanam Bewafa (1991)

And many more......

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مجھے ہے حکمِ اذاں