1. In your admin panel navigate to Tools then Select Image Handler from the drop-down.
You will see this:

2. Next: Select the product category for the product you wish to add more images to from the drop-down shown in the image above. Your screen will look like this:

3. You can then select the product you wish to add more images to then press the display button.
Now click on the new file button. You will see this:

On the panel on the right in the screenshot above find this:
Image suffix (optional)
Enter a specific suffix or leave empty for automatic suffix generation.
Enter 02 for first additional image 03 for second additional image, and so on.
You will then click on the browse button under the Default Image to select your image, then click on save. Your screen will look like this:

To add more images to this product select the product from the drop-down (step 3).
You may select to “refresh the page” instead of going back to step 3.
Continue this until you have uploaded all the additional images for this product.
Follow this process for each product that you wish to have additional images for.
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