Yes, it's called pediophobia (http://en.wikipedia.org/wiki/Pediophobia). It's a general fear and everyone has at least some fear or more. Some people don't like going up elevators; don't like heights (vertigo); don't like flying; hate Spiders, snakes or bugs in general. There are many fears out there and everyone has one fear they generally don't like to talk about. Your chances of ever being in a situation with a mannequin is slight. If you are in a store move somewhere else. Better still, face your fears? Pull apart your fear and ask yourself what on earth a mannequin could possibly do to harm you. YOU ARE IN CONTROL! I do believe that there should be a phobia name for fear of mannequins; I am so scared of them. Whenever I go shopping, I get the feeling that they will come to my house and turn me into one of their kind. God! Some of them don't even have heads or arms or legs! If someone who reads this belongs to NASA could you please make up a scientific name for mannequins!?!?!?!?
Pediophobia
There is no official phobia name for the fear of vipers. However the official phobia name for the fear of snakes is ophidiophobia.
There is no name for fear of olives, but lachanophobia is the fear of vegetables.
Hylephobia is the name of the phobia related to the fear of materialism
Ballistophobia is the name of the phobia related to the fear of missiles
Limnophobia is the name of the phobia associated with the fear of lakes
Traumatophobia is the name of the phobia relating to the fear of injury
Ideophobia is the name of the phobia relating to the fear of ideas
Patroiophobia is the name of the phobia relating to the fear of heredity
Geliophobia is the name of the phobia associated with the fear of laughter
Mnemophobia is the name of the phobia related to the fear of memories
Genuphobia is the name of the phobia relating to the fear of knees
Sophophobia is the name of the phobia relating to the fear of learning