Create a spreadsheet document then input below data to A1:C24.

The data successfully created in the new spreadsheet

Select the whole data range then Select main menu 'Data-)Filter-)Standard Filter'

Pop up 'Standard Filter' dialog

Set the Filtering options in 'Field name', 'Condition' and 'Value'.say : Field name='Month'; Condition='='; Value='Feb'

Click 'More' button and check the radio button 'Case sensitive'

Distinguishes between uppercase and lowercase letters when filtering the data

Check "Copy results to" check-box and specify a place for the new data then click OK button

Filtered data will be copied to new place. Rows which have 'Feb' should be shown, rows which have 'feb' should not be shown

Repeat Step3 - Step7 set Value='feb' then Click 'OK' button

Filtered data will be copied to new place. Rows which have 'feb' should be shown, rows which have 'Feb' should not be shown

Repeat Step3 - Step7, clear the  'Case sensitive' check-box

Both items of 'Feb' and 'feb' will be shown