What ever one you use you wont see a big difference on dial up with the speeds,download managers are ok for continuing dloads if you get cut off but most don't boost the speed.As for using 2 download managers i dunno if there is an advantage or not.
OnePlus 5T review: Hands-on
Illustrator Andrés Lozano on his improv line work, brazen use of colours & hand sketching
iPhone X review
Comment envoyer gratuitement des gros fichiers ?