Duplicate images for gallery post

Hi all! I’m new to WordPress and Minimatica and just starting my photo blog. I’m creating a post with a number of images and I’m getting duplicates. I see both the thumbnails as well as the images. To add the images, I use the Insert button, select an item from the Media Library, then select Insert Into Post. I’m pretty sure this is not what I want to do.

I’ve had limited success with Attaching images to the post; I don’t get duplicates, but this requires me to perform a search to do the attachment. For 20 images, this is just not fun!

Is there an easy way to get 20 images into a single post? I was hoping I could just go into the library, click 20 check boxes and put the images into a post…

Thanks in advance for any help!