I was at yet another conference the other day, and there were some East Coast bigwig historians there. Two of them pronounced didn't as one syllable, leaving out the second 'd'- i.e., dint.
    This got me thinking a little bit. In India one hears didn't pronounced dint rather often among the anglophone set, but I assumed it was just an Indianism. But then I heard these two East Coasters talking that way, and then I remembered my dear friend Sybille, who, when I met her, routinely spelled the word dint in school papers. When I questioned her about it, she seemed unaware that there was more than one 'd' in didn't, and she too pronounced it dint.
    Me myself, I have always pronounced it as two syllables- di'n. No final 't', but two syllables: did or di' and n. I also sometimes drop the initial 'd' and say idden or i'in, as in 'I i'in go to work yesterday". (This might be a personal peculiarity; I don't really know.) In the case of i'in, it might be chopped down to one syllable (iin) if I'm talking fast.
    I don't know how common dropping initial consonants is, but I do it often: gonna becomes unna (or a schwa); think becomes ink or 'nk, etc. (I 'nk I'm unna go to bed.) Well, that's how I talk, anyhow.