Hello Thilini,
In that help.sap link it says
"One of the advantages of this architecture is that a work process can include connections to several different databases belonging to different manufacturers.
To use DB Connect to transfer data into BI, you need to have installed the SAP-specific part of the database interface, the DBSL, for the corresponding source-database management system for each BI application server."
Installing the Database Shared Library (DBSL) - Business Intelligence - SAP Library
The original files can be overwritten only if the names of the Oracle specific ones are the same with the SQL-specific ones. Please download the Oracle DBSL once and check if they have same names with your SQL DBSL files. If not you can be sure that you put them under your kernel directory safely. Normally they have different names and you are able to put them under DIR_EXECUTABLE.
For general information:
400818 - Information about the R/3 database library
I hope they help.
Regards,
Serhat