Hey ploenpin,
First of all, I am basing this response on several assumptions, so please correct me if I am mistaken:
(1) you're in your early twenties, between 21-23
(2) you either are about to graduate college or have been out for about 1 year.
(3) you've had trouble breaking into IB
(4) these are 1 year programs
I will admit that I don't know much about the relative strengths of these programs, but I do know a handful of people that did similar 1 year programs, like a Masters in Finance at IESE or boutique and tech / business hybrid programs. In general these people got pretty solid positions put of school for someone with their experience level, however their success was largely based on how much they hussled (and by hussle I mean worked and networked hard).
I took a quick look at the employment reports of these two programs and it appears as if they have largely similar outcomes. Olin looked more "finance related", which is no surprise given the emphasis in the title. However, it looks like ther are a decent amount of banking jobs at both programs and it can be assumed that the smaller amount of people at Duke going into finance is probably due more to the more generalized nature of that program as compared to the MSF at Olin.
In my opinion, for what it's worth, I would base the decision on a couple of things. (1) How sure are you on I-banking? If you're all in, Olin appears to be the better program. If you might consider other positions, Duke looks better. (2) Do you want to live in the Midwest or Southeast, (3) do you want to pursue a MBA later on? While I wouldn't put too much emphasis on this last point, but if this is something you want to pursue later, I think it might make more sense to do the MSF as you will have an opportunity for a more generalized management education later on and possible transition out of banking if you decide that is not what late twenties you wants to do.
Assuming you are set on pursuing a finance role out of school and wouldn't mind spending 3-4 years in the Midwest before applying for a MBA, I would lean towards Olin here. Feel free to PM me as well.
Best of luck with you choice!