My nephew is having his Bar Mitzvah and we are a family of Kohens. My older Brother was hoping to be called for the first Aliyah and wanted to honor me with either the 4th or 7th one. The Rabbi at the shul however says that only one Kohen is to be allowed. I understand that this can be an Ashkinazi tradition but am curious how common this is. Is it true that other Ashkenazi Rabbis would allow a second Kohen just as long as two Kohens aren't called back to back, or is that a Sephardic tradition. The Shul is in Boston and is considered Traditional/unaffiliated. The Rabbi is a graduate of Hebrew College Rabbinical School.
: נהגו לקרות כהן אחר כהן בהפסק ישראל ביניהם ואומר החזן כשקורא לשני אע"פ שהוא כהן וכיוצא בזה נוהגים בלוי אחר לוי
הגה: ולכן מותר לעלות ג"כ למפטיר בכי האי גוונא ואם קורא מפטיר סתם אין לחוש לפגמו דהרי לא מזכיר שמו. וי"א דאין לקרות כהן או לוי למנין ז' אבל לאחר שנשלם המנין יכולים לקרות כהן או לוי. [אגור בשם מהרי"ו ומרדכי פרק הניזקין וב"י בשם ר' ירוחם] וכן נוהגין במדינות אלו ומיהו במקום צורך ודחק יש לסמוך אסברא ראשונה
The custom is to call up two Kohanim with a Yisroel between them. The Chazan should say when he calls up the second Kohen “even though he is a Kohen” and this is the custom with calling up a Levi after a Levi. The Rema says that “therefore it is allowed to call up a Kohen for maftir. If he reads maftir without being called then there is nothing to worry about. (And there is an opinion that we do not call up a Kohen or Levi to the 7 people called on Shabbos. But after the 7 have been called, it is possible to call a Kohen or Levi) and this is the custom in these places. But when it is necessary and difficult to do otherwise, one can rely on the first view.”
You are curious how common this is. In many years, I have never seen a Kohen called up in an Ashkenazi shul other than first, for Maftir or after the 7 people.
The only time that as a Kohen, I was not called for one of these aliyos, was when I was called up in a Sefardi shul with the words of the Shulchan Oruch "אע"פ שהוא כהן".