Most certainly. A back agraffe, such as those in old Sohmer pianos and in Stuart & Sons pianos now, changes the vector at which the string is attached to the plate, from horizontal (as in all modern pianos except for Stuart & Sons) to vertical. The concept behind this is that a vertically attached string will vibrate perpendicularly to the soundboard, theoretically resulting in better vibration. In practice, much sympathetic vibration is lost, resulting in a sound that while very clear, may lack in warmth to certain tastes.
Naturally, the agraffes holding the strings in the back are subject to much more tension than "horizontal" bridges and pins, because there is no diffusion of the tension. Thus, in old Sohmers it is quite common to find agraffes that simply give.
I think it is basically the same principle you use when opening a bottle of beer.
...thinking of which...