How many multi hours you get in independent on whatever route you choose.
For example,
Scenario A) SE CPL, MEP then IR.
25 hours SEP CPL training
6 hours MEP training + test (1hr)
15 hours multi IR + test (2hrs)
Gives 24 hours TT multi.
Scenario B) ME CPL then IR
22 hours SEP CPL training
6 hours CPL training + test (2hrs)
15 hours multi IR + test (2 hours)
Give 25 hours TT multi
All the above assumes minimum hours blah blah blah. There are benefits to doing a multi CPL.
First, there is also a financial saving as follows. You SEP instruction is reduced by 3 hours, saving about £500.
There is no difference in the cost of hiring for test whichever route you go. Take the cost of a twin hire for a CPL test is around £600, contrast that to the hire for a MEP (£300) and SEP for CPL test (£350). Not a lot in it.
Second, you will save is the £100 to the CAA for adding the MEP to your licence, which they gratefully do for free in your CPL was performed in a MEP.
However where you will lose out is if you do not pass first time, in minimum hours as the subsequent cost of hire and re-training will soon eat into the savings listed above. Remember that it is quite a step from a simple SEP to a complex MEP, with only 6 hours to get it all ready for a CPL test.
Good luck whatever way you go. Oh, and I have yet to meet any employer who gives a rats derriere about what you did you CPL in.