Sometimes creates spurious fiducials in map

[davecrawley]

Have observed that sometimes we see in map.txt things like the following:

000 0.000000 0.000000 909652020
250 1.593955 -1.723141 0.383688 84.229730 5.831001 -153.464171 2754444.730460 0
300 1.214587 0.405905 0.464756 79.848916 3.751515 -63.024089 0.000000 0

250 and 300 are legitimate fiducials and the only fiducials present, what the others are is unknown.
rostopic echo /fiducial_map yields

  - 
    fiducial_id: 250
    x: 1.593955
    y: -1.723141
    z: 0.383688
    rx: 1.47008611657
    ry: 0.101770166137
    rz: -2.67845506779
  - 
    fiducial_id: 300
    x: 1.214587
    y: 0.405905
    z: 0.464756
    rx: 1.39362648835
    ry: 0.065476288688
    rz: -1.09997786112
  - 
    fiducial_id: 926101810
    x: 0.0
    y: 0.0
    z: 1.89297659238e+93
    rx: 1.57079632679
    ry: -1.57079632679
    rz: 0.0