Nov 28 2018
Feb 24 2017
Feb 21 2017
No, it's not.
They are equivalent as to what is being transcluded (which is "B" in both cases) but they are not equivalent as to what is being shown in template page itself.
The first one shows "A" in template page.
The second one shows "AB" in template page.
Jan 8 2017
I forgot to mention that I am using MW 1.26.2 and cannot upgrade because Media Temple, my hosting provider, still uses and old PHP version. But I did a thorough search about this issue and I believe that still exists in latest MW.