My son is [name_u]Lennox[/name_u], which 3 years later is still my favourite name of all time. As you can see from my signature, I’m considering [name_m]Franklin[/name_m] as baby #2’s name, in part because it’s a family name, and in part because I think [name_m]Frank[/name_m] on a sweet little baby boy is adorable.
However, my trendy (ish) surname for son #1 would be a very different style than my old man name for son #2. The only saving grace I can think of is that they are both very hipster (as are we) Thoughts?
[name_u]Lennox[/name_u] and [name_m]Franklin[/name_m] are very hipster which I love
[name_m]Len[/name_m] and [name_m]Frank[/name_m] are very sweet on two little boys and I think they can also grow with it well. As a sibset it flows nicely while being different names. [name_m]Franklin[/name_m] may seem old man like but I think names like [name_f]Frances[/name_f], [name_m]Fredrick[/name_m], [name_m]Theodore[/name_m] are in a revival period right now and actually seem fresh, new and cute. If you love it, and I do! you should totally name your little one [name_m]Franklin[/name_m] 
The notion that a “sibset” must match is very much a nameberry thing. Siblings (and their names) are not sets of fine china. [name_u]Lennox[/name_u] and [name_m]Franklin[/name_m] are great together.
I think they work well together