In awk: awk '{arr[$1][length(arr[$1])+1]=$2}; END {for (i in arr) {printf i;if (length(arr[i])>1) {xc=" [";for (rr in arr[i]) {printf xc;printf arr[i][rr];xc=","} print "]"} else print arr[i][length(arr[i])]} }' yy

Output:

hmz_age:'21'
fd_year_svp:'1982'
fd_year_anne:'1987'
name: ['tom','hmz','toli']
school: ['anne','svp']
status_tom_mar:'yes'
tom_age:'31'
toli_age:'41'
status_hmz_mar:'no'

In awk: awk '{arr[$1][length(arr[$1])+1]=$2}; END {for (i in arr) {printf i;if (length(arr[i])>1) {xc=" [";for (rr in arr[i]) {printf xc;printf arr[i][rr];xc=","} print "]"} else print arr[i][length(arr[i])]} }' data.txt

Output:

hmz_age:'21'
fd_year_svp:'1982'
fd_year_anne:'1987'
name: ['tom','hmz','toli']
school: ['anne','svp']
status_tom_mar:'yes'
tom_age:'31'
toli_age:'41'
status_hmz_mar:'no'