Dieline discrepency

Hi, all. I am hoping you can help me fix this dieline size discrepency.

The .dxf dielines that I use are created in Inventor by an Engineer (not myself). When I open that .dxf dieline in Adobe Illustrator, it measures 300 mm width x 600 mm height and has a corner radius of 3mm. The dieline is .709 pt. The stroke is aligned to the center. But, when I copy and paste that same dieline and/or place it into my Indesign file, the dimensions change. The dimensions in InDesign are larger—the dieline measures 300.25 mm width x 600.25 mm height with a corner radius of 4.233 mm. If I align the stroke to the inside, the dimensions change back to 300 mm x 600 mm (which is correct), but the corner radius stays the same, 4.233 mm. I need the corners to be 3 mm.

How do I fix this? I am hoping to create a workflow that is uncomplicated, and doesn’t require many steps. I have thousands of graphics that have this issue. The dimensions of my Indesign file should match the .dxf dieline.

I’ve attached screenshots that show the dimensions and corner radius in both Illustrator and Indesign. One screenshot shows two dielines that are overlayed—I wanted to see if the corner radius actually was changing when bringing it from Illustrator to Indesign. The green dieline is one that I created myself (300 mm x 600 mm, 3 mm corner radius). The red dieline is the .dxf file that has the 4.233 mm radius. You can see the size difference most clearly in that screenshot.

Thank you.