In the 2024 PHB the language for Tool Proficiency reads: 

If you have proficiency with a tool, add your Proficiency Bonus to any ability check you make that uses the tool. If you have proficiency in a skill that’s used with that check, you have Advantage on the check too.

So does this mean that

1) I'm rolling Sleight of Hand for a tool check but I don't have proficiency in Sleight of Hand, I add my proficiency.  If I do have proficiency already in Sleight of Hand, then I roll with advantage. OR

2) I'm rolling Sleight of Hand and I already have proficiency in Sleight of Hand, I have Advantage on the roll and still add my tool proficiency. 

I'm assuming it is scenario (1), but the way they tried to simplify the language of the text leaves it kind of vague. "[A]dd your Proficiency Bonus to any ability check...If you have proficiency in a skill that’s used with that check, you have Advantage on the check too."

Does this also mean that Rogues will basically ALWAYS have Advantage on lockpicking with Thieves Tools? 

If you are proficient in Sleight of Hand and proficient in Thieves Tools and have Thieves Tools available, you will have advantage on the check.

Quote from Tilda_Wildbramble >>

If you are proficient in Sleight of Hand and proficient in Thieves Tools and have Thieves Tools available, you will have advantage on the check.

 But still no double advantage, correct? That seems like it would be a bit much. 

Quote from Enigma2057 >>

Quote from Tilda_Wildbramble >>

If you are proficient in Sleight of Hand and proficient in Thieves Tools and have Thieves Tools available, you will have advantage on the check.

 But still no double advantage, correct? That seems like it would be a bit much. 

You are correct in thinking that there is no double advantage.