Montresor uses the name Luchesi throughout the story in order to entice Fortunato to accompany him to his palazzo and through the subterranean passages. For example,
“Come,” I said, with decision, “we will go back; your health is precious. You are rich, respected, admired, beloved; you are happy, as once I was. You are a man to be missed. For me it is no matter. We will go back; you will be ill, and I cannot be responsible. Besides, there is Luchesi—”
Poe has Montresor say that Fortunato is "rich" because this tells the reader that Fortunato is capable of buying a whole shipload of Amontillado and making a huge profit. Montresor could probably only afford to buy a few more casks (if they existed); but he needs money badly. Fortunato would have no qualms about buying the entire cargo and cutting Montresor out of the deal. Fortunato would consider that an "excellent jest," whereas Montresor would consider it another of the thousand injuries of Fortunato--if it really happened.
Fortunato may be jealous of Luchesi, but his main motive for insisting on sampling the wine himself is that he does want Luchesi to hear about the Amontillado Montresor says he just acquired at a bargain price. Montresor keeps threatening to go to Luchesi, although he has not the slightest intention of doing so, since he doesn't really have a cask of Amontillado to sample. Montresor is only after Fortunato. Luchesi never appears in the story. Presumably Luchesi would be keenly interested in Montresor's Amontillado because it was a bargain. All three of these men must earn their livings by dealing in expensive luxury goods. They all have to be knowledgeable about such things as oil paintings,s antique furniture, jewelry (gemmary), and gourmet wines. They also have to be knowledgeable about potential buyers as well as potential sellers. A "pipe" contains 126 gallons. Neither Montresor, nor Fortunato, nor Luchesi would be interesting in buying that much Amontillado for personal consumption.
Fortunato could have told Montresor that he had a bad cold, that he was unsuitably dressed to go down into the catacombs, that he had been drinking pretty heavily, and that he would be glad to sample the Amontillado tomorrow but not tonight. He is interested in Montresor's wine only because it was a "bargain," but he does not have to go to Montresor's palazzo in order to sample it. He can go directly to the waterfront and find the ship which he thinks must have brought the casks of wine in from Barcelona. However, he realizes that Montresor is in a big hurry because he wants to buy a few more casks before word gets around that it is being sold at a bargain price. If Fortunato doesn't go home with Montresor, Montresor will go straight to Luchesi--so he says. Then Fortunato would be competing with an affluent business rival for the Amontillado and driving the price up. Montresor has to get Fortunato to his palazzo immediately because he doesn't want to give him any time to tell other people he is going to see Montresor--or any time to make inquiries about the supposed arrival in port of a shipment of wine from Barcelona.
If Fortunato finds that Montresor's wine is genuine Amontillado, he has no intention of telling him so--and Montresor knows it because he knows Fortunato's character and business practices from long experience. Fortunato would shake his head and say it is nothing but ordinary sherry. He even indicates that that is his intention when Montresor first tells him about it.
“My friend, no. It is not the engagement, but the severe cold with which I perceive you are afflicted. The vaults are insufferably damp. They are encrusted with nitre.”
“Let us go, nevertheless. The cold is merely nothing. Amontillado! You have been imposed upon. And as for Luchesi, he cannot distinguish Sherry from Amontillado.”