Transform dataset into sequence set in R

Question

I am an absolute beginner with R, so I'm sorry in advance for this probably simple question...

I have an excel dataset that looks like this:

Now, I need to transfirm this data into a sequence format so that I have the following:

1. headers for each columns from year 00 to 20 for each of the columns A and D so that it follows this pattern: 00A|00D|01A|01D|02A...|20D where each number represents the year and each letter either column A or column D
2. ridding out the duplicate ISINs and implement the corresponding year activity (A and/or D) in the appropriate year row columns created in step 1

Based on the above example, I want to end up with this:

Is there any way to perform such an operation?

Thank you so much in advance!