When you declare a Variable within your pages, you might include it more than once, and this will cause the error.

When usng the ADOVBS.inc file, you might mistakenly use it more than once within your pages, and if you do, you will receive the following error.

To recreate this error, include the ADOVBS.inc file within your pages more than once.

To correct this issue, make sure that you only include the ADOVBS.inc file one time within your files.
This situation also applies to using DIMs

If you use DIM MyVar and later redeclare DIM MyVar.
You will get this error as well.