DocuSign: How to prefill multiple text tabs with the same label?

The post you referenced is now out of date - there's actually a trick you need to do when you have multiple tabs with the same label that you want to prefill with the same value.

Basically if you have several tabs with the same tabLabel and you'd like all of them to start out with the same initial value then you need to prefix the tabLabel with the wildcard string

\\* 

For instance, let's say you have a social security tab that you've added to your document in multiple places called "SocialSecurityTab". To fill ALL of the textTabs that contain "SocialSecurityTab" as their tabLabel use the following JSON:

"textTabs": [
      {
        "tabLabel": "\\*SocialSecurityTab",
        "value": "012-34-5678"
      }

It's important to not forget both backslash (\) characters, and also make sure you're not using a system (such as Salesforce) that might strip one of backslashes out for various reasons.

Documentation

See the Automatically Populating Tabs documentation for more info.