MINUS (or weird) start/end frame in JSON generated by "Button combinations"

[Kounotori-ssbm]

Frequently, Clippi generates a json file with weird frame times like below.

{
  "mode": "queue",
  "replay": "",
  "isRealTimeMode": false,
  "outputOverlayFiles": true,
  "queue": [
    {
      "path": "C:\\Users\\Kounotori\\Game\\Melee\\FM-Slippi-2.0.0-Win\\Slippi\\20200714\\20200714-0921_(Fox)-vs-(Falco)_BF.slp",
      "startFrame": -123,  //??
      "endFrame": 0,  //??
      "gameStartAt": "07/14/20 9:21 am"
    },
    {
      "path": "C:\\Users\\Kounotori\\Game\\Melee\\FM-Slippi-2.0.0-Win\\Slippi\\20200714\\20200714-1424_(Puff)-vs-(Fox)_YS.slp",
      "startFrame": -123,  //??
      "endFrame": 4,  //??
      "gameStartAt": "07/14/20 2:24 pm"
    },
    {
      "path": "C:\\Users\\Kounotori\\Game\\Melee\\FM-Slippi-2.0.0-Win\\Slippi\\20200714\\20200714-1431_(Puff)-vs-(Fox)_PS.slp",
      "startFrame": -123,  //??
      "endFrame": 3,  //??
      "gameStartAt": "07/14/20 2:31 pm"
    },
    {
      "path": "C:\\Users\\Kounotori\\Game\\Melee\\FM-Slippi-2.0.0-Win\\Slippi\\20200714\\20200714-1431_(Puff)-vs-(Fox)_PS.slp",
      "startFrame": -6,  //??
      "endFrame": 834,  //??
      "gameStartAt": "07/14/20 2:31 pm"
    },
    {
      "path": "C:\\Users\\Kounotori\\Game\\Melee\\FM-Slippi-2.0.0-Win\\Slippi\\20200714\\20200714-2148_(Fox)-vs-(Sheik)_YS.slp",
      "startFrame": 1203,  //correct
      "endFrame": 2043,  //correct
      "gameStartAt": "07/14/20 9:48 pm"
    },
    ...
  ]
}

whats this frames?
I think no one inputs the button combination (I use A+Dpad-down) on that frame.

"startFrame": -123, appears most frequently.
And "endFrame": 3, and "endFrame": 4, also appears frequently.

[vinceau]

As discussed over Discord, I'm pretty sure this is a non-issue.