At this point, Ran is just trolling. There no way she can still doubt Conan is not Shinichi. I know she don't have insane deduction skills but come on, how many proofs do you need for acknowledge that ?
@Lilliwyt Basically, she is in denial. She took baths with him, sleep together, etc. She is too embarrassed to admit that she had done all those things with Shinichi.
Momiji is the culprit. She hired one of the brothers to do it so there'd be a tiebreaker.
@Lilliwyt@miyako19
Also, at what point does "the guy shrunk back down to a 6 years old" sound like a logical explanation? Especially when she's seen both Shinichi and Conan at the same time and place a handful of times.
Ah yes, the Kyoto way of being mean. I remember someone from Osaka saying they're so polite in Kyoto, when a restaurant wants you to leave they offer you another cup a tea, hoping you'd take the hint.