Funny thing: after the scene where the police officer (Josh Hartnett) spots a blonde girl in the park, chases her down and takes her to the police station, I thought this blonde girl was supposed to be the one resembling Hillary Swank. The same girl also did these lesbian scenes with Elizabeth Short. The actress playing the blonde is Jemima Rooper. Google her name with Black Dahlia. You'll see that she looks quite like Hillary Swank. But apparently Elizabeth Short was still the one who was supposed to be Hillary Swanks lookalike.

Oddly enough, though, in one picture I've seen, Elizabeth Short did look a good deal like Hilary.
Only in Show Biz by injection

I didn't understand this casting at all. Both actresses did their jobs very well, but looked nothing like each other. What's weird is that with prosthetic makeup to broaden Swank's face and a hairdresser who knew what he/she was doing, they could have done a much more convincing job of creating "look-alikes" (or "look-a-lot-like-each-others"). Betty Short's hair, as shown in all the "screen tests", was shorter and much curlier than Madeline's; how hard could that have been to accomplish? This was unforgivably sloppy work. Too bad we couldn't have had a time warp for this film. Sherilyn Fenn did look
a lot
like Mia Kirschner, and probably had the chops to act the Madeline role as well as Swank did (Swank was terrific IMO), if only Fenn were 25 years younger.
I'm only in Show Biz by injection

PS, but they didn't look alike at all, in my opinion. Not enough for mistaken identity or anything like that.

Well, while I would think that was the case. Madeleine says that she just HAD to meet this girl, because everyone said they looked so much alike. So they met up a year prior.

They were supposed to behave and dress alike not be dead ringers for each other, is what I got out of it.

De Palma should have had Hilary Swank play both parts; it would have been easy since they have no scenes together. A major blunder on his part.
I liked Mia Kirschner's approach to her part, she brought out the wistfulness and need for affection the girl had.

She should've played both parts.

It wouldn't suggest Hollywood's look-a-like-mania.
"You couldn't be much further from the truth" -
several

Here's a thought: perhaps they should have cast Kerschner in
both
roles.
http://hexfan.proboards.com/

No. De Palma does not support this view. He exposes it in all its Hollywood vanity and narcissism.

I do see the resemblance. But I don't know anything about Dushku's acting ability, which would have to be formidable to do what Hillary Swank did with this role, looks aside. I wish the film had some makeup people competent enough to make Hillary's eyes look bigger (do-able) and to do the prosthetic work required to give her broader cheeks (also do-able). That alone would have made a huge difference. But what really ticks me off is that they didn't even bother to curl Hillary's hair more or cut it to look something more like Kirschner's even wigs would have been better! This was really sloppy work, and it was so glaring that it noticeably detracted from what I thought was a wonderful movie. I can't fault anyone's acting, but the "look-alike" aspect was laughable.
I'm only in Show Biz by injection

I personally would have cast Eliza Dushku. She has at least a passing resemblance to Mia Kirshner.

Definitely. If they didn't keep mentioning this supposedly resemblance I would have no idea those characters were even meant to look alike. It was far from the only flaw in the movie but quite a big one, given how central it was to the plot.

I know! I have no idea who did the casting but it was so off.

you are sooo right! Rose McGowan resembled the murder victim far more.