Who Are Members of Grand Lodge?
The first time some Pennsylvania Freemasons attend a Communication of the Grand Lodge of Pennsylvania, they are curious as to why they are directed to sign a visitor's slip and not a member's slip and why they are not eligible to vote in Grand Lodge. Not every Pennsylvania Freemason is a member of the Grand Lodge.
Article 3.01 of the Ahiman Rezon defines the composition of the Grand Lodge to be: "... the Grand Officers, Past Grand Masters, Past Deputy Grand Masters, Past Grand Wardens by two years of service, Past Grand Treasurers and Past Grand Secretaries by six years of service, (and the following of Subordinate Lodges*) Past Masters by one year's service, and Masters and Wardens of all Lodges lawfully warranted and duly constituted by it, and under its Jurisdiction."
Simply stated, Masons who are not members of the Grand Lodge as defined in the Ahiman Rezon, are invited and as welcome to Grand Lodge Communications as visitors, just as they regularly visit from one Blue Lodge to another.
[Source: The Ahiman Rezon (updated to March 2001). *Parenthetical clarification, "and the following of Subordinate Lodges" added for this explanation.]

Faith and Support Kept Work Going on Masonic Temple
In March of 1869, nearly a year after the laying of the Cornerstone for the Masonic Temple in Philadelphia, the Building Committee "... contemplated the cessation of all active operations upon the new Masonic Temple except ... (to) square up the work, put the property and adjacent streets and sidewalks in a good and safe condition, ... until the sum of $250,000 shall have accumulated in the Building Fund."
Fortunately, that cessation never occurred. Grand Lodge was convinced of the enthusiasm and support of the Brethren across the Jurisdiction and, with an abiding faith in fraternal dedication and fiscal creativity, the Building Committee determined to continue the construction. The results verify that the Brethren were overwhelmingly responsive.
[Source: Report of the Building Committee of Temple entitled "IN RE. BUILDING THE TEMPLE, From the Minutes," April 7, 1869.]

Dual Membership is a Specific Number
Dual membership has been permissible in Pennsylvania since the adoption Dec. 1, 1993 of Article 19.09 in the Ahiman Rezon. "Dual" means two and that limitation is cited in Article 19.09, as follows:
"A member of a Lodge in this Jurisdiction is permitted to be at the same time a member of one other Lodge either in this or in another Jurisdiction. A member of a Lodge in another Jurisdiction may be at the same time a member of one Lodge in this Jurisdiction. ..."
Unless he formerly held primary membership in Pennsylvania, the petitioner for dual membership must be a resident of Pennsylvania if his primary membership (now) is in another Jurisdiction. (In that case) his former Pennsylvania Blue Lodge is the only Lodge to which he may apply for dual membership in a secondary Lodge.
[Sources: The Ahiman Rezon (updated to March 2001 (*Emphasis of "one" added for this explanation) and The Secretary's Manual.]