I need an excel formula when a value is one sheet is entered, it will populate two rows in another sheet

I need help with this Excel scenario…

In Sheet1, when I enter a “reference number” in cell A1, it should populate the same value in cells A1 and A2 in Sheet2.

Then…

In Sheet1, when I enter a “reference number” in cell A2, it should populate the same value in cells A3 and A4 in Sheet2.

And so on…

Appreciate any help.

Thank you!