In App.config you need to add one more connectionString add key with different name.
Check the below Settings how add multiple Connection string with different name so can use it by referring with name as ConString or ConString1.
<connectionStrings>
<add name="ConString" connectionString="Server=.\SQL2005;Database=Test;uid=sa;pwd=pass@1234;" providerName="System.Data.SqlClient"/>
<add name="ConString1" connectionString="Server=.\SQL2005;Database=Sample;uid=sa;pwd=pass@1234;" providerName="System.Data.SqlClient"/>
</connectionStrings>