Unfortunately, two preset managers in one schematic is not advisable.
Although it may appear to work correctly within SM, it will not work right when you export your design as a VST plugin. This is because the manager acts as the "communication channel" to the VST host - and the host will get very confused when it sees two preset managers.
What will happen will probably depend on your host - certainly preset changing/storage/loading will be corrupted, but some hosts may even crash when you load the plugin.
However, the kind of thing you want to do may still be possible. A search for "preset manager" will find several alternative designs that users have posted - some are much better than the standard manager when you need large amounts of presets.
Feel free to use any schematics and algorithms I post on the forum in your own designs - a credit is appreciated (but not a requirement).
Don't stagnate, mutate to create. Without randomness and serendipity the earth would be just another barren rock.