... And here's the proof!
This is probably the first sound sample on the Timepass pages!
One of the FIRST movies I EVER saw (I was 3, maybe 4 years old at the time, and that was before we had our good old Tesla TV at home) was Ek Duje Ke Liye. (1979 or 1980??) I remember very clearly that my aunt sneaked idlis into the theater but the usher shone his torch on us and asked us not to eat outside food in the theater. What a ripoff. But - before I digress.

I only remember snapshots from the first time I saw this movie. Yes, friends and neighbours, I DID watch it a second time, millions of years later, in bits and pieces. It was after I knew that Kamal Haasan was a giant douche, and wanted to watch him make a complete ham ass out of himself once again in the TV room at PD Block in IISc. That was ONE reason I saw a bit of this movie. A minor reason was to watch the ultra hot Rati Agnihotri for a bit, but the most important reason I wanted to watch this movie for the second time was the title song, Hum Bane, sung by SPB and Lata. (I think? Who else has that eldritch shrill voice?) SPB has always been a source of entertainment for us, because of his awesomely bad southie accent when he sings Hindi songs. But he really really went over the top in the title song to Ek Duje Ke Liye.

A little background: the movie story is as follows. In this Romeo and Juliet ripoff, Kamal Haasan is a southie who doesn't know much Hindi and goes to the same college as his neighbour-cum-lover Rati Agnihotri who of course is a meat-eating northie. Of course, their families don't approve of their love, so they do whatever they can to separate them. Kamal goes away for a while, and comes back all well-versed in all kinds of Hindi (He gives her family a demonstration, even uses some Bambhaiyya Hindi - at least that's what the stereotypical naukrani bai says - "Aai ga, Bambhaiyya bolto" - which is bullshit, of course. Any half-assed dipshit who lives in Bombay for more than a year will talk BETTER than Kemel saar did in this film. And NO ONE, repeat, no one will ever say "Aai ga, Bambhaiyya bolto!") which he learnt, for some bizzare reason, while learning Bharatnatyam under Madhavi (Gult actress). So there are two awesomely bad nuggets of Hindi movie songs before he becomes the "language expert". One of them is the title song, the other one, almost as good as the former, is of course the elevator love song, Mere Jeevan Sathi. It took me a while to understand that it was funny because he was actually reciting names of (then) famous Hindi movies. I know, I'm dumb. Anyway, that song is awesome. It not only features an awesomely bad SPB, it also is made up of, as I said, Hindi movie names from the late 70s, AND it features Anuradha Paudwal in one of her first songs. Of course, she has very little to do in this song other than giggle and say a couple of words now and then. It took her at least five more years to find Gulshan Kumar's ass so she could kiss it. But once again, I digress.

Since KH's Hindi isn't so perfect at the beginning of the movie, they probably told SPB - "Try as much as possible to make your accent really bad" (Which I'm sure wasn't too difficult for SPB anyway!) And here's the result:

Link to Hum Bane, Tum Bane Ek Duje Ke Liye.

Not only is SPB's accent to credit for this awesome sound clip, the lyricist has to be showered with gold and jewelry and milk and honey and all that stuff. Cum fast, cum fast, don't be slow, indeed! One day I will gather enough courage to visit SPB and wash his feet with rose water.

Afterthought
I have mentioned the following incident in another Timepass article. A conversation with Subroto that went something like this:
Sundar: I once read something in a newspaper about how many couples in Ahmedabad were inspired by Ek Duje Ke Liye and committed suicide by drowning themselves in Kankaria Lake.
Subroto: Saala aisa picture rahega to suicide nahin karega to aur kya karega!