I would like to see the source, I want to see if I can make a short verified description of it for posting.
From Wiki, other sources at bottom.
In most denominations of the Latter Day Saint movement, a high priest is a member of the priesthood within the Melchizedek priesthood order. High priests are typically older and more seasoned leaders within the priesthood. The term derives in part from the Epistle to the Hebrews which describes Jesus as “a high priest after the order of Melchizedek.” (5:10; see also 6:20). Movement founder Joseph Smith, Jr. ordained the first high priests on June 3, 1831.[1]
All Bishops are “High Priests” in the Melchizidek priesthood. Scripture states that office only belongs to Christ.
I can give you more LDS sources but here are a few...
http://www.lds.org/scriptures/bd/high-priest?lang=eng
Here is LDS justification for it...http://ldsdoctrine.blogspot.com/2008/05/great-high-priest.html
http://eom.byu.edu/index.php/High_Priest
Let me know if you need more.
Christians know there is only ONE High Priest not thousands.
All Bishops are High Priests in the Melchizidek priesthood. Scripture states that office only belongs to Christ.
This statement is mine not from the wiki (LDS) article. Just to clarify