Receiving two different values for same date for Landsat B8 using Google Earth Engine

Question

I am extracting values of the B8 of Landsat8 in Google Earth Engine and for several month I receive two very different values for the same date and cannot find the issue.

How can I handle this?

My code:

var maskL8 = function(image) {
  var qa = image.select('BQA');
  /// Check that the cloud bit is off.
  // See https://www.usgs.gov/land-resources/nli/landsat/landsat-collection-1-level-1-quality-assessment-band
  var mask = qa.bitwiseAnd(1 << 4).eq(0);
  return image.updateMask(mask);
}

var start = '2020-07-01';
var finish = '2020-07-30';
var pt = ee.Geometry.Point([-49.31582, 69.56833]);
// Map the function over one year of Landsat 8 TOA data and take the median.
var l8 = ee.ImageCollection('LANDSAT/LC08/C01/T1_TOA')
.filterDate (start,finish)
.filterBounds(pt)
.map(maskL8);


//Map.addLayer(B8);
//Map.addLayer(pt);
Map.centerObject(pt, 16);

print(l8);





// B8 VALUE OF PT 

var myB8 = l8.select("B8"); 
print("myB8",myB8); 

var getB8 = function(image) {

  // Reducing region and getting value
  var value_B8 = ee.Image(image)
    .reduceRegion(ee.Reducer.first(), pt)
    .get('B8');

  return value_B8;
};

var count = myB8.size();

var B8_list = l8.toList(count).map(getB8);

print("B8 list", B8_list);

var img = l8.first();

Map.addLayer(img);
Map.addLayer(pt);

var allDates = l8.aggregate_array('system:time_start');

var allDatesSimple = allDates.map(function procDates (ele) {
  
  return ee.Date(ele).format().slice(0,10);
  
});

var paired = allDatesSimple.zip(B8_list);

print (paired);

Answer 1

There is a night-time image in the collection on that date. You can easily see this if you display the footprints:

You can skip those by limiting the WRS_ROW property to be <= 122.

var l8 = ee.ImageCollection('LANDSAT/LC08/C01/T1_TOA')
  .filterDate (start,finish)
  .filterBounds(pt)
  .filter("WRS_ROW <= 122")
  .map(maskL8);