myvar = request.GET['myvar']

<class 'django.http.QueryDict'>

for var in request.GET['myvar']:
    print(var)

5
6
7

<QueryDict: {u'myvar': [u'123', u'567']}>

request.GET.getlist('myvar')

res_set = request.GET.copy()
for item in res_set['myvar']:
    item
...