Hello,
Thank you for the kind words regarding our hard working data entry staff and the service. I can fix this issue you for you if you just want to send your Logbook Pro backup (File..Archive..Backup) in a support ticket and clearly specify what you want merged into what.
If you want to do it yourself, here is the way to go about it. In the Spreadsheet Style data entry area, click the "Aircraft Make & Model" (Type) column header, this will force a sort on this column grouping your C-152 and C152 entries. If you find one set of rows is smaller than the other, change the smaller list to the Type of the other. So if you have fewer C152, change them to C-152, or vice-versa, it doesn't matter which, we just need to consolidate it to one, then we can change it with the final option below with one shot. Before you change a type, select the text in the Ident column and press CTRL+C as when you change the type it's going to change the N-Number on you! After copying the Ident, press SHIFT+TAB to "back tab - left" and then change the type, press TAB then CTRL+V (Paste). Do that for each row.
Once you have the Type changed, whichever one does NOT exist any more, delete from the Options...Aircraft Area. Now for the remaining type, i.e. C152 or C-152, rename the existing entry in the Options...Aircraft area and it will automatically and instantly rename all of those types in the Spreadsheet log area.
If you do decide to do it yourself, BACKUP your data file PRIOR to doing this work so you can fall back to the backup if needed. Again, I'll gladly fix this for you if you'd like us to do it, just submit a ticket with your data file and request.