2 cameras render same canvas?

I want to create a screen shot with my game's logo stick on it so I add another camera just to make the logo only visible for it, because I don't want my player to see this logo when playing the game.
But the problem is that when I render this camera to a texture in code, my main canvas doesn't get rendered! Just only the logo because its canvas render mode set to "screen space - camera" but on my main canvas it is set to "screen space - overlay". So I just want to add this main canvas to my second camera when rendering.
Thank you in advance!