I mean, the Soviet version of the B29 had extra rivet holes because one of the B29s they reverse engineered had a manufacturing mistake. Would they trust their engineers to make a close copy that wasn't exactly the same aerodynamically? I know that's in a different era of the USSR, but still.
When you encounter things you don't understand in complex engineering it's not unwise to copy them because you are either copying a harmless mistake, irrelevant appendix type feature or it's a key feature you don't yet understand.
Plus the cost overhead for a few more rivets isn't crazy; even if they're superfluous and you know it, better to spend brainpower on more complex and critical engineering.
