If I use the files from the toppar subdirectory of the c44b2 distribution (14 Feb 2020), I do get the error; the NH2 CT2 CD angle term is repeated in both par_all36_prot.prm and par_all36m_prot.prm, leading to the level -1 error. The term is also repeated in the files from the July 2019 bundle on the MacKerell lab web site (or was when I downloaded it a year ago).
The force constants and equilibrium angle are slightly different.
Update: The error does NOT occur if the FLEX keyword is used, e.g.
read param card flex name par_all36_prot.prm
In general, you should use the FLEX keyword, so this is not a major issue.
Last edited by rmv; 07/18/20 11:13 PM.