fixed bug that was causing duplication in data

[adosib]

See https://stackoverflow.com/questions/56262318/caretcalibration-duplicating-data-when-including-multiple-model-columns-in-the.

[codecov-io]

Codecov Report

Merging #1038 into master will decrease coverage by 0.04%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1038      +/-   ##
==========================================
- Coverage   32.72%   32.68%   -0.05%     
==========================================
  Files          90       90              
  Lines       13597    13597              
==========================================
- Hits         4450     4444       -6     
- Misses       9147     9153       +6

Impacted Files	Coverage Δ
R/safs.R	63.04% <0%> (-0.52%)	⬇️
R/gafs.R	65.51% <0%> (-0.23%)	⬇️

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[topepo]

Thanks