Here is what usually happens. The time that you do have at home with your dog is now shared with a stranger (your new dog). Your dog #1 never has you to himself. Since dog #1 does not pick dog #2, there are often personality clashes. Now we have two dogs that are not getting their needs met. You have two dogs fighting over your attention when you get home. You have double the vet bills.
Now… here is a better solution.
Use the money that you would have spent on the second dog and hire a dog walker for your dog, and/or send him to doggy daycare one or two days a week.
Make sure that you spend at least one hour a day giving your dog your undivided attention. Learn to make time to enjoy the dog that you have. Remember why you wanted a dog in the first place. Learn about dog friendly events in your area and go and share them with your best friend. Your dog will love you all the more for it.
The harsh reality is that If you do not have one hour per day to spend with your best friend, then you should find someone who does, and consider getting a cat or fish for yourself.
Remember, you have your job, your friends, your family, your social life…..
All your dog has is you. He loves you unconditionally. He does not need another dog, he needs you.