when someone has a cake idea, i usually find myself searching on here at photos to get some ideas...then find myself using maybe 2 or 3 diffferent cakes from here, to end up with a design. (so basically cake a,b,c...and i like 1 idea from a, 2 ideas from b and so on). So is that okay to do? Or if someone see's a cake they like, and want you to duplicate the design...Is that okay?

I don't think it's uncommon to search the Internet for inspirational photos and ideas, getting ideas from many different sources.
I've had people send me emails asking me if I mind if they copy one of my cakes! When they do that I am always happy to see their rendition of my ideas, but when someone copies an idea and doesn't ask me, or give credit, then most decorators get a bit offended....
A simple email goes a long way in developing respect and even friendships with other decorators. I've found that Most people are willing to help you out if you just send them an email!

I always tell people that I can not duplicate someone elses design, but that I can do my interpretation of it in my own style. People usually understand that we cant just steal designs from other people but we can use them as inspiration.

It wouldn't hurt to send a message to the decorator and ask if they mind.
I've gotten emails from other decorators who like certain designs and ask if they can make a similar cake. Since I'm a "hobby baker" I usually don't mind and I ask to see pictures of the finished cake, just 'cuz I like to see other people's work. If the design is their trademark or a signature piece for them, then they might not be as receptive.
The only problem I have is when people take the pictures I've posted of my cakes and claim them as their own.

Some people are awesome and can come up with completely orignal ideas with otu any problems.

The rest of us, need inspiration.

The way I feel is that if someone doesn't want a cake design copied they shouldn't share it with the world on a public message board (or any other public website).

It is considered good manners to credit people if you borrow their design. If I copy something out right I'll say so. If I borrow ideas from different cakes, then to me it starts taking on a new design.