Good word from our Lord.
Heres a few others where "Lord, Lord" is at which could also be helpful.
Starting off with the one you posted
Mat 7:21 Not every one that saith unto me, Lord, Lord, shall enter into the kingdom of heaven; but he that doeth the will of my Father which is in heaven.
Mat 7: 22 Many will say to me in that day, Lord, Lord, have we not prophesied in thy name? and in thy name have cast out devils? and in thy name done many wonderful works?
here was the issue,
Mat 7: 23 And then will I profess unto them, I never knew you: depart from me, ye that work iniquity.
Mat 7:24 Therefore whosoever heareth these sayings of mine, and doeth them, I will liken him unto a wise man, which built his house upon a rock:
Mat 7: 25 And the rain descended, and the floods came, and the winds blew, and beat upon that house; and it fell not: for it was founded upon a rock.
Mat 7::26 And every one that heareth these sayings of mine, and doeth them not, shall be likened unto a foolish man, which built his house upon the sand:
Mat 7:27 And the rain descended, and the floods came, and the winds blew, and beat upon that house; and it fell: and great was the fall of it.
An the context being them which acknowledge him (because they say unto him "Lord, Lord")
Mat 7:21 Not every one that saith unto me, Lord, Lord, shall enter into the kingdom of heaven; but he that doeth the will of my Father which is in heaven.
Even though many will acknowledge him as Lord Lord, as the foolish (which hear and do not do) adress him the same
Mat 7: 22 Many will say to me in that day, Lord, Lord, have we not prophesied in thy name? and in thy name have cast out devils? and in thy name done many wonderful works?
He professes he does not know them and will profess to to these to depart from him "ye that work iniquity"
Mat 7: 23 And then will I profess unto them, I never knew you: depart from me, ye (((that))) work iniquity.
Whereas here Paul says,
2 Ti 2:19 ((Nevertheless)) the foundation of God standeth sure, having this seal, The Lord knoweth them that are his. And, Let every one ((that)) nameth the name of Christ (((depart from))) iniquity
So he knoweth them that are his, and Paul tells them (who name his name) to depart from iniquity
It would be far better to name his name and depart ((from)) iniquity then to name his name and be asked to depart ((from)) him for working it.
Mat 7: 23 And then will I profess unto them, I never knew you: depart (((from me))) ye that (((work iniquity))).
Because it says, he gave himself to redeem us from all iniquity
Titus 2:14 Who gave himself for us, that he might redeem us from all iniquity, and purify unto himself a peculiar people, zealous of good works.
God sent Jesus first to bless in this manner
Acts 3:26 Unto you first God, having raised up his Son Jesus, sent him to bless you, in turning away every one of you from his iniquities.
Following the same theme in blessing you is in turning every one of you from his iniquities
As Paul saying,
Romans 6:10 ...as ye have yielded your members servants to uncleanness and to iniquity unto iniquity; even so now yield your members servants to righteousness unto holiness.
Turn away from the same, or from yielding yourselves unto iniquity and begin yielding your members to righteousness
Even as the grace of God teaches us the same thing
Titus 2:11 For the grace of God that bringeth salvation hath appeared to all men,
Titus 2:12 Teaching us that, denying ungodliness and worldly lusts, we should live soberly, righteously, and godly, in this present world;
Lord Lord is shown in those who do not do as he says
Luke 6:46 And why call ye me, Lord, Lord, and do not the things which I say?
And here showing not everyone who says to him Lord, Lord shall enter the Kingdom...
Mat 7:21 Not every one that saith unto me, Lord, Lord, shall enter into the kingdom of heaven; but he that doeth the will of my Father which is in heaven.
And of those who do the will of God are shown considered as family
Mark 3:35 For whosoever shall do the will of God, the same is my brother, and my sister, and mother.
And this is the will of God also
1 Thes 4:3 For this is the will of God, even your sanctification, that ye should abstain from fornication:
Which would also make sense of this as well (along with)
Heb 2:11 For both he that sanctifieth and they who are sanctified are all of one: for which cause he is not ashamed to call them brethren,
Theres a few for you, maybe these would be helpful to your study