So, yeah, I checked that. In Blender the animation was 60 frames. Exporting at 60 FPS should give 1 second of animation. However, the render setting in the options was set to 24 FPS, causing a strange export (it was like 2 and a half odd seconds in Godot). This was the first thing I checked. In the Godot import settings, it was set to 60 FPS, which should have brought it in correctly, but I guess there is a double conversion happening. However, even after I fixed it in Blender (to be 60 FPS) it was still 1.017 seconds in Godot (one extra half frame). I manually changed it to 1.0 second, but that did not fix it. I even tried putting wild values for the timeline, like 0.8 seconds or 1.5 seconds. In either case, there was a slight pause (looked like 1 or 2 frames) and then an interpolation, to the first frame. The one thing I did not try was deleting the last frame in Blender, and allowing Godot to do it's interpolation. I imagine this might result in acceptable behavior, but the fact that the animation works in Blender, Unity, and Unreal, leads me to think there is a bug.