Hi,
thanks for your question.
The “Custom CSS” textarea on the “Plugin Options” screen is the common CSS input field for all tables, at the same time. All the CSS has to be inserted there, as there no such thing as an individual “Custom CSS” textarea for each table.
So, instead of overwriting the CSS of the first table, just append the CSS of the second table to the CSS of the first table in that “Custom CSS” textarea.
Regards,
Tobias