What you state concerning two experiences is a somewhat common belief. However, I don't see that confirmed within scripture.
Prior to His resurrection, Jesus told His apostles that the Holy Spirit was currently with them but would be in them in the future. We know He was speaking of the Holy Spirit that was in Him at that time. (Col. 2:9) That's why the Holy Spirit could not come until Jesus departed.
See John 14:16-20,
"And I will pray the Father, and he shall give you another Comforter, that he may abide with you for ever;
Even the Spirit of truth; whom the world cannot receive, because it seeth him not, neither knoweth him:
but ye know him; for he dwelleth WITH you, (meaning while Jesus was currently with them) AND shall be IN you. (a reference to a future experience)
I will not leave you comfortless: I will come to you.
Yet a little while, and the world seeth me no more; but ye see me: because I live, ye shall live also.
At that day ye shall know that I am in my Father, and ye in me, and I in you." Jesus' statement in verse 20, is a reference to what first occurred at Pentecost and remains true today. People know they have been indwelt by the Holy Ghost as evidenced by speaking in tongues:
"And when the day of Pentecost was fully come, they were all with one accord in one place.
And suddenly there came a sound from heaven as of a rushing mighty wind, and it filled all the house where they were sitting.
And there appeared unto them cloven tongues like as of fire, and it sat upon each of them. And they were all filled with the Holy Ghost, and began to speak with other tongues, as the Spirit gave them utterance.,,," (Acts 2:1-4).
Peter went on to say, "This Jesus hath God raised up, whereof we all are witnesses.
Therefore being by the right hand of God exalted, and having received of the Father the promise of the Holy Ghost, he hath shed forth this, which ye now see and hear (Acts 2:32-33). What did they hear? Speaking in tongues by those who were filled with the Holy Ghost.
Think about it. All of the other detailed conversion accounts also involve one Holy Ghost experience, not two (Acts 8:12-18, 9:17-18, 10:43-48, 19:1-7, ). Saul/Paul didn't receive the Holy Ghost during his encounter with Jesus on the Damascus road. God actually sent
Ananias to Paul for that very purpose (Acts 9:17-18). Consider Paul's question to the men of Ephesus , "Have you received the Holy Ghost since you believed?" (Acts 19:1-7) Paul's words reveal a person can believe in Jesus yet still need to receive the Holy Ghost. And notice Philip knew the Samaritans who already believed the gospel and were water baptized did not receive the Holy Ghost until days later (Acts 8:12-18). Peter stated he and others knew the Gentiles had received the Holy Ghost when they heard them speak in tongues (Acts 10:43-48).
Lastly, does it make sense that a person that already has the Holy Ghost requires a second experience in order to empowered?