Renaming variable cells using VBA

Dear community,

I am a beginner in VBA programming and I am grateful for any advice you can give me in order to solve the following problem:

How can I rename a cell's content? The complication is that the word that I would like to rename exists twice in a given table.
Let me give you an example:
The word "Material" exists two times in a table. In order to use vlookup in a later processing stage, I would like to rename the first "Material" to "Material1" and the second "Material" to "Material2". "Material1" and "Material2" are not fixed to a certain cell. Indeed, the cells vary on a daily basis. I thought about renaming them on the basis of a particular cell range (let's say that "Material1" is definitely within the range of A200:A300 and "Material2" within the range of A500:A600").

Any idea how I can achieve that result?

Thanks for all your helpful comments!