Excel copying a worksheet from a workbook to another

If I understand your question properly, you need to do this in two steps. For clarity, I've named the workbooks and worksheets in brackets:

1) Copy worksheet across from one workbook (Workbook 1) to another (Workbook 2). Step by step guide for this at https://www.ablebits.com/office-addi...other-workbook

2) There's no replace worksheet function, so if the worksheet you copy across (Workbook 1 Sheet A) has the same name as another worksheet already in Workbook 2 (Workbook 2 Sheet A) , it will rename itself as Sheet A (1). Manually delete the original Workbook 2 Sheet A, and rename Workbook Sheet A (1) as appropriate.