The NoDev versions have the OPL_IS_DEV_BUILD commented out when compiling so it saves its settings to the CFG folder.
In other words, the NoDev versions reverts this change:
rev852 - Change version to 'OPL 0.9.4 WIP', re-enable development build flag - Fri Oct 23 04:16:22 2015 -0400

The non NoDev versions have the dev flag on so they save to CFG-DEV, as the developers intended.

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Comments from SP193 why you should not use this version unless you know what you're doing:
The DEV option is not only for show; compatibility modes between different OPL versions may change and games may not require the same compatibility modes between the stable and development versions.
This is why we decided that such a design must exist; the user can then retain his parameters for the stable version. Not to mention that allowing the settings for the two types of versions to mix will cause version-management in OPL-CL to not work (submissions for the stable version could be newer than the one for the development version, causing updating to not work right).

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Source Location. Comment it out to disable DEV (Do not set 0):
Include/opl.h
#define OPL_IS_DEV_BUILD 1 //Define if this build is a development build.