浏览器有重复的cookie变量

My cookies has 2 values for the same variable:

slng=zh; HstCfa1189204=1435218026929; HstCmu1189204=1435218026929; HstCla1189204=1437300574160; 
HstPn1189204=11; HstPt1189204=26; HstCnv1189204=8; HstCns1189204=12;
last_position=styles%2F; slng=vi

slng variable has 2 values. I'm using php setcookie with syntax setcookie('slng', "vi", 0, "/", "");

Please help me fix it