This is simply FYI. Perhaps someone else can benefit from these discoveries? 

I was building a custom plugin that took a wpDT datatable and integrated it with Google Maps.

1) The wpDT ID (that you use in the shortcode) is NOT an identifier across wpDT. A given id actually also has a column mysql_table_name. So you get to the table with the data you have to do a look up for the mysql_table_name in the wp_datatables table. 

 2) The mysql_table_name naming convention for new wpDT tables is interesting. A new table gets a sequential #. But a duplicated table retains the name of the parent table, and add a _# (underscore . int) to that name. I'm not sure what happens when you dupe a duplicate.  

 3) On the front end, the wpDataTables (js) object uses a property name for each displayed table that has no relation to the mysql_table_name or the original ID. Mind you, within a given table object is a property getting back to the mysql_table_name, but it's not a key per se, if you know what I mean.   

 Long to short...

each table has multiple "unique identifiers" so if you're expecting some sort of consistency, there is none. I'm sure there are good reasons for this. I'm not going to guess what they are. But I wish I knew these things soon rather than later. They are not, best I can tell, in the docs. So I'm sharing here.  You're welcome.