Geeta ji has sung very few songs with playback singer Mahendra Kapoor ji. MK arrived late on the playback singing scenario and by that time Geeta ji's career was suffering due to personal issues. Also, MK's favorite composer Ravi had Asha ji as his favorite singer from his debut film. When OP was composing songs for MK, Geeta ji was already out of his recording room.
The only known songs sung by these two are "Oh bedardi kyon tadapaye" composed by Pandit Ravi Shankar ji and "Hain aag hamare seene mein" where Geeta ji gets to sing 2 lines. I think this is the only song she sang in a Raj Kapoor film (except for the film "Ab dilli door nahin" where she gets to sing 2 duets with Asha ji)
Here is a list of songs sung by Geeta ji and Mahendra ji
(1) Gham ki aag mein ham to jalte yehan- Geeta Dutt , Mahendra Kapoor (MD : S N Tripathi) Pareeksha
(2) Hai aag hamaare seene mein - Geeta Dutt , Lata Mangeshkar , Manna Dey , Mahendra Kapoor , Mukesh (MD : Shankar Jaikishen) Jis Desh Mein Ganga Behti Hai (1960)
(3) Jhoomo re jhumne ke din aaye - Geeta Dutt , Mahendra Kapoor (MD : Suresh Talwar) Fashionable Wife
(4) Ladkaiyan ma wa jab i chohna to jawaani ma ka - Geeta Dutt , Mahendra Kapoor (MD : S N Tripathi) Jogin (Bhojpuri)
(5) O bedardi kyon tadpaye jiyara mora rijhay ke - Geeta Dutt , Mahendra Kapoor (MD : Pandit Ravi Shankar) Godaan
(6) O mister johnny mizaaj kaisa hai - Geeta Dutt , Mahendra Kapoor - Tarzan & Captain Kishore (1964)
(7) Rukh pe paaudar lab pe surkhi - Geeta Dutt , Mahendra Kapoor (MD : Basant Prakash) Hum Kahan Ja Rahe Hain
(8) Sagre bahnwa se samujhe na manwa ho - Geeta Dutt , Mahendra Kapoor ( MD : S N Tripathi) Jogin (Bhojpuri)
(9) Sun re o chhaliya bole kya paayaliya - Geeta Dutt , Mahendra Kapoor - Lady Of The Lake
(10) Parwana Kehta Kya Afsana- Geeta Dutt , Mahendra Kapoor - (MD : Bulo C.Rani) Black Tiger
(11) Aadami gharib ho..Sambhalo dil zara - - Geeta Dutt , Mahendra Kapoor - (MD : Kalyanaji Anandji) Dil bhi tera hum bhi tere
Songs 1,4,6,7,8,9 are not available in my collection. Requesting generous HF members to share the same
Thanks
Parag
P.S. Thanks to Erum ji for providing the name of the film for the song no 6.