hi @Pratibha_Mallya
Similar question was posted earlier today actually and what you want to achieve is not supported by Campaign.
The Tracking label is created and stored when a Delivery is saved and as such you can have only 1 label per URL per delivery and it is the reason in the sample you provide you will see that the label in the tracking logs and reporting will just be <%recipient.firstName%>"
Full answer here but in your scenario the proposed possible workaround won't apply as you've got a unlimited recipient first name in your target...
https://experienceleaguecommunities.adobe.com/t5/adobe-campaign-classic-questions/url-label-issue/m-...
Hope this helps,
Thanks
Denis