Coordinates changes when Importing Geotag

I found out some issue while work in Pix4D mapper.

When I add images in a project, the geotag data was changed automatically in a last few digits. I tried to import geotag from coordinates text file using a geo-coordinate system(WGS84), but after importing, the coordinates was changed a little bit.  ex) 39.1234 567 ->39.1234 987

Can I trust the coordinate converted by this?

Even I get geotag from RTK GPS, but the quality report gives a 1~2m absolute accuracy to me. So, I’m thinking this could cause the error in the project.

Do you have an example of your input data?
It should be formatted as: imagename, longitude [decimal degrees], latitude [decimal degrees], altitude [meter]

If you have an RTK GPS, please make sure you have either included the accuracy of your measurements in the input file (as follows), or that you edit the image geolocation accuracy in the user interface so that it corresponds to the accuracy of the measurements (by default it is 5m and 10m): 

If you have the orientation parameters (omega, phi, kappa) and accuracy, it would be: 
imagename, longitude [decimal degrees], latitude [decimal degrees], altitude [meter], omega [degrees], phi [degrees], kappa [degrees], Accuracy Horz [meter], Accuracy Vert [meter]

More here: https://support.pix4d.com/hc/en-us/articles/202558539-Input-Files#label2

If you do not have any Ground Control Points (GCPs) in your project, the absolute accuracy is based on the image geolocation. Hence, if the accuracy of the measurements is not correctly set, it will have a repercussion in the quality report. 

Let us know how it went