How to reproduce:
1. Open the attached 2019.3.0f5-775655.zip project
2. Open Scenes/SampleScene
3. Select Cube GamObject in the Hierarchy window
4. Go to the Timeline window and extend the recorded clip (inspect ExtendRecorderTrack.wmv video for better reproduction steps)
5. Enter the Recording mode and select some keyframes of different attributes
6. Try to add a key a bit further from the attributes

Expected: All selected keyframes of Animated Values attributes are added when "Add Key" is pressed in the set timeline position

Actual: Only one of the selected keyframes of Animated Values attributes are added and not in the chosen position (see the ExtendRecorderTrack.wmv video)

Reproducible with: 2019.3.3f1, 2020.1.0a25

Notes:
- Could not test on earlier versions because of the thrown errors