troubles when 2 webbrowser navigate simultaneously

[ofthewood]

dear all,
In excel userform , i've put 2 webbrowser objets.
Before show them , I start the navigation with the following statements :
userform.webbrowser1.navigate "https ....1" 'note it's https URL
userform.webbrowser2.navigate "https ....2"

Sometimes , information is not complete for one of the webbrowser,
sometimes information of webbrowser1 is displayed in webbrowser2 .....

Does webbrowser accept simultaneous navigation ?

Thank's for your anwsers.