Dear Rabbi, If there is only one Levi in Shul, and that Levi "has Maftir" (i.e., will be called up Maftir and subsequently sing the Haftorah and associated berachot, as is the custom in my Shul) can he also be called up to the Levi’s portion (i.e. the second aliyah) or should the Cohen be called up ’bimcom Levi’
Shalom, Thank you for your very interesting question. As you know there is a Rabbinic decree to call up a Cohen first then a Levi, and one can not forgo this law, even if the Cohen or Levi agree to forgo their honor. On the other hand, one should not call up someone who has already been called up once for a second aliyah to read the Maftir and Haftorah, unless there is no one else able to read the Haftorah (see Shulchan Aruch, Orach Haim, 282, 5 in the Rema). So, in your situation we have a problem - on the one hand you need to get called up for the Maftir so you can read the Haftorah as is traditional in your Shule. On the other hand you are the only Levi and therefore need to get called up second. There are some Rabbis who allow one in such situations to get called up twice, but others say it is better for the Levi to leave Shule before the second aliyah so there will be no Levi present, and the Cohen we get the second aliyah, and then the Levi will return to Shule and be called up Maftir. The second opinion is quoted as the correct thing to do in the work Piskay Teshuvot (Shabbat 282,9 (second edition)). If there is a Rabbi in your Shule you should certainly approach him with this question and follow his ruling, which as I wrote could be either of these options. If you are Rabbiless - then you should follow this ruling and leave the Shule before they the second aliyah, and return after they the Cohen makes his (second time) blessings. Blessings.