IS it possible to use two objects as command parameter?

Firstly, if you are doing MVVM you would typically have this information available to your VM via separate properties bound from the view. That saves you having to pass any parameters at all to your commands.

However, you could also multi-bind and use a converter to create the parameters:
Firstly, if you're doing MVVM you would typically have this information available to your VM via separate properties bound from the view. That saves you having to pass any parameters at all to your commands.

<button content="Zoom" command="{Binding MyViewModel.ZoomCommand" commandparameter="{Binding" elementname="MyCanvas," path="Width}"<br" mode="hold" />    <button.commandparameter>
        <multibinding converter="{StaticResource YourConverter}">
             <binding path="Width" elementname="MyCanvas" />
             <binding path="Height" elementname="MyCanvas" />
        </multibinding>
    </button.commandparameter>

In your converter:

public class YourConverter : IMultiValueConverter
{
    public object Convert(object[] values, ...)
    {
        return values;
    }
    ...
}

Then, in your command execution logic:

public void OnExecute(object parameter)
{
    var values = (object[])parameter;
    var width = (double)values[0];
    var height = (double)values[1];
}