Frame rate discrepancy

[looklook]

Hello

I'm trying to make copies of various segments of a gameplay video. The video I'm using is 59.94fps, the copy that Avidemux makes is 60fps.

What am I doing wrong? The start and end-point is on a keyframe. The file is an MP4. Output is set to MP4 Muxer.

Video and Audio set to copy.

I'm using Avidemux 2.8.1

Should I be using a different version?