Using the twins patch with update 18 is a problem even without using unren (which enables the developer console).
The underlying cause is the duplication of some return labels (in the original version it is duplication of _call_angles_23 and _call_angles_24). When the code hits the "call angles" which uses the first instance of the duplicated label, it will execute the call and then return control to the second instance of the duplicated label instead of going back to the first. In this case you'll jump from partway through scene 67 over to part way through scene 71. The posted modified versions fixed the original duplicated labels, but created some different ones, so they aren't really a fix.
If you have the developer console enabled it detects the error at startup and throws the exceptions so you know what to fix, but that isn't what is causing the bug.
The underlying cause is the duplication of some return labels (in the original version it is duplication of _call_angles_23 and _call_angles_24). When the code hits the "call angles" which uses the first instance of the duplicated label, it will execute the call and then return control to the second instance of the duplicated label instead of going back to the first. In this case you'll jump from partway through scene 67 over to part way through scene 71. The posted modified versions fixed the original duplicated labels, but created some different ones, so they aren't really a fix.
If you have the developer console enabled it detects the error at startup and throws the exceptions so you know what to fix, but that isn't what is causing the bug.