how to split values inside column and create two differents table?

Assuming you want every input line to be represented in both output files:

$ cat tst.awk
BEGIN { FS=OFS="\t" }
NR == 1 {
    str1 = str2 = $0
}
NR > 1 {
    str1 = str2 = $1
    for (i=2; i<=NF; i++) {
        split($i,a,/,/)
        str1 = str1 OFS a[1]
        str2 = str2 OFS a[2]
    }
}
{
    print str1 > "foo"
    print str2 > "bar"
}

$ awk -f tst.awk file

$ head -50 foo bar
==> foo <==
samplexxx       EH      Tred    GangSTR
dijen006_100    17      17      10
dijen006_75     .       .       .
dijen017_100    17      17      12
dijen017_75     17      21      20
dijen081_100    17      17      10
dijen081_75     17      17      18
dijen082_100    21      21      14
dijen082_75     22      22      21
dijen083_100    20      20      10
dijen083_75     20      20      19
dijen1013_100   17      17      9
dijen1013_75    18      17      17
dijen1014_100   17      17      8
dijen1014_75    18      18      18
dijen1015_100   nofile  .       7
dijen1015_75    16      16      15
dijen402_100    21      21      9
dijen402_75     27      21      18

==> bar <==
samplexxx       EH      Tred    GangSTR
dijen006_100                    17
dijen006_75
dijen017_100    21      21      17
dijen017_75                     20
dijen081_100    20      20      19
dijen081_75                     18
dijen082_100    22      22      22
dijen082_75             27      21
dijen083_100                    20
dijen083_75                     19
dijen1013_100   20      20      19
dijen1013_75    20      20      19
dijen1014_100   18      18      17
dijen1014_75                    18
dijen1015_100                   15
dijen1015_75                    16
dijen402_100    31      29      27
dijen402_75     31      38      36