When creating the instance "dynamically" store the UID in some array. Or use an instance variable that is different for each instance of the object so that you have a reference that allows you to pick only the specific instance you're looking for.
If you want to have different instances of a same sprite displaying different frames, be sure to load/display the correct animation frame and have the animation at a speed of 0 so the frames won't switch.
Perhaps you're asking the wrong question here though and should actually explain exactly what you are trying to achieve to see if the current method you are applying is the most appropriate.
Also, as you can see I moved your topic as it is an help request that fits better to the "How do I" forum.