I've noticed that some of my latest engine designs automatically create extra engine designs at half the size. My first thought after, "Why is the technology report for engines so crowded?" was, "Wow, free half-size engine designs!" Alas, although they crowd the tech report screen, they don't show up as components I can build on the Design Screen. Reviewing it just now, this only seems to occur with commercial engines.
I suppose I could delete the extraneous designs in SM? I've been obsoleting the designs so I have less to scroll through, so they aren't in my way at present, but I'd like to know deleting them outright won't cause me problems.