javascript - Double Alert Windows -

i getting double alert prompts single form: alert pops first time, when click ok, same 1 pops open again. think code should alert once when hits "else window.alert(samewarning) , stop when reaches "return false()"; seems return false() causing alert twice. maybe because have 2 forms on 1 page; yet, have 2 separate function names ("signinform()" , "savesignup()")and call 2 separate forms (forms[0] , forms[1])? think code correct, can't figure out @ point. appreciated. in advance!

<script type="text/javascript"> //first function forms[0] function signinform(){          // var samewarning = "the required fields not submitted following error(s).  \n \n";         var warninglogin = "the following field(s) require entry: \n \n";         var samewarning = warninglogin;          var username = document.forms[0].username.value;         var pswd = document.forms[0].pswd.value;          if(username == ""){          samewarning += " - first name \n";         }          if(pswd == ""){          samewarning += " - password \n";         }          if (warninglogin == samewarning){              return true;              }          else  {              window.alert(samewarning);           }     return false;       }  //second function call forms[1]  function savesignup(){          // var warning = "the required fields not submitted following error(s).  \n \n";         var warning = "the following field(s) require entry: \n \n";         var same = warning;          var firstname = document.forms[1].firstname.value;         var lastname = document.forms[1].lastname.value;         var email = document.forms[1].email.value;         var phone = document.forms[1].phonenumber.value;          if(firstname == ""){          //firstname.style.backgroundcolor="red";         warning += " - first name \n";         }          if(lastname == ""){          warning += " - last name \n";         }          if(email == ""){          warning += " - email \n";         }          if(phone == ""){          warning += " - work phone \n";         }          if(phone < 5 ){             warning += " - must numberssss \n";             }          if (warning == same){             return true;          }           else  {              alert(warning);                  }     return false;    }  </script> 

html

<h1>login</h1> <form method="post" onsubmit="return signinform();" action="" >     <input type="text" placeholder="username/email" name="username">     <input type="password" placeholder="password" name="pswd" id="pswd">     <input type="submit" onclick="signinform();" value="sign in"> </form> <h1>sign up!</h1>     <form method="post" onsubmit="return savesignup()" action="" >     <input type="text" placeholder="first name" name="firstname">     <input type="text" placeholder="last name" name="lastname">     <input type="text" placeholder="email" name="email">     <input type="text" placeholder="phone number" name="phonenumber">     <input type="submit" onclick="savesignup();" class="button wide" value="request account">         

when click submit, first fires click event (calling function), fires submit event (calling function again). remove onclick submit buttons.