Replacing strings in vector: Every instance replaced by previous found instance

I'm working with a lot of text files I have loaded into R and I'm trying to replace every instance (or tag) of </SPEAKER> with a certain string found earlier in the text file.

Example: "<BOB> Lots of text here </SPEAKER> <HARRY> More text here by a different speaker </SPEAKER>"

I'd like to replace every instance of "</SPEAKER>" with the name of, say "<BOB>" and "<HARRY>" based on the NAME that has been found earlier, so I'd get this at the end:

"<BOB> Lots of text here </BOB> <HARRY> More text here by a different speaker </HARRY>"

I was thinking of looping through the vector text but as I only have limited experience with R, I wouldn't know how to tackle this.

If anyone has any suggestions for how to do this, possibly even outside of R using Notepad++ or another text/tag editor, I'd most appreciate any help.

Thanks!