Chance of funding while applying for multiple PhD programs at the same school I found the same question in here, however, my story is a little bit different:

I contacted a faculty member in one of the US institution and he promised an admission. But, for the chance of funding, he suggested me to apply to two programs, and I did so. Recently, I've noticed he is a faculty member at another program (third program) too. I asked him whether he recommends applying for the third program. His response was "I'm involved in this program as well. The chances of funding are pretty good. I would suggest you modify your statement...".

My question is does applying for three separate PhD programs can significantly increase the chance of funding? or conversely, as some stated before, does it have a negative impact on my application?

This professor is a faculty member in all three programs, and they are placed in different colleges.
This answer is coming very late, but may be useful to people who land up on this thread. By referring to different departments, I mean different PhD programmes. 

Regarding the PhD application: 

Since the same professor is in all the three departments and he is conducting research which are aligned with your research goals, there is no harm in applying to all 3 programs. It may make a stronger case for your selection as well (not a guarantee always, but no negative impact surely). The graduate committee is made of professors who are very well aware of the fact that almost all phd applicants apply to multiple phd programmes, the difference here is that they know where 2 other applications of yours went. They may ask you to set a priority, that's all. Showing interest is different from receiving an offer, professors may be interested in multiple candidates, but due to constraints give out offers to a smaller pool. They should not hold anything against you. If they do, you are better off not joining that programme.

I applied to 3 phd programmes in the same university, and got selected in my second choice. All 3 departments knew that I had applied to the other 2 as well. They had no issues with it.

Regarding funding: 

Often different departments in the same university have different ways of selecting candidates and providing funding. In my case, two of the departments gave out department-centralized PhD offers, where we would have to choose our advisor after joining the programme. However in the third department at the same university, funding was through the grants of individual faculty. So the PhD advisor was fixed from the beginning, and the funding was specific to that project's requirements. You would have to ask the graduate programme manager for exact details.