System Information
Win 7 Nvidia card

Blender Version
2.79

Short description of error
I want create an animation transforming plane to sphere by using Bend modifier and after Apply as Shape Key, but the result is not identic.

Exact steps for others to reproduce the error
1- Create a plane, switch to Edit mode, SY2. then use a loop cut to divide it into two squares, then subdivide;
2- Add a Simple Deform modifier, set deform method to Bend, use a new empty object as its origin, select the empty, then RX90.
3- Add another Simple Deform modifier, also set deform method to Bend, use a second empty object as the origin, select the empty, then RX90, RZ90.
4- At frame 1, set 0 as the Angle value for both Bend modifiers, insert keyframe for them. Then jump to, say, frame 60, set 180 for the first Angle, 360 for the second Angle, again, insert keyframe for both.
5- Apply as shape key the first modifier and after the second.
6- Set 1 for the first shape key (plane is becoming a half cylinder it is normal).
7- Set 1 for the second shape key . Here is the problem , it is not a sphere.

I'm not sure if it is the good site to report this problem , thank you for your help !