What 'those' extra lines? Do you mean the small 'share a coffin' text? I remember this small remark was in vanilia game, Sure there were extra lines in mods, but I don't think the 'share coffin' was added by these mods.
That's bad that I am dead sure about the share coffin line being in vanilia... :/

I verified: the 'share coffin' lines are in the Enhanced Edition. So, my memory is better than those who say it was only some modded texts.

I'm playing the enhanced edition and they don't seem to be there. Also I checked a Let's Play on Youtube of the original and they weren't there either (though I may have missed it as I have little patience for sitting through LPs), so I guess my memory's off in that regard.

Unless you're talking about a regular conversation (text only) - something similar definitely comes up in that (both EE and original).

I definitely didn't get a random banter-like thing happening - I remember this happening quite a lot in the mortuary, but as has been said this is most likely due to Qwinn's patch and wasn't in the original this way either.

Mh,

activated Banter Accelerator from Qwinns Tweak Pack? AFAIR those lines where not within the restored Mortes Intro Fix, but occured in vanilla PST as in patched ones - But I am really not sure....
And Morte telling you not to go for the female ones (Yeah, you know They are dead, we are dead - they appreciate the death expierence in us... etc., etc. "blink, blink") is right to be experienced by the player in the second room after you got the keys to open that door within - even - the PST:EE edition....

Try "more interjections" from tweaks anthology? Not sure if it will install on PST.