I’ve seen it looked down on a lot throughout the discussions just want to know why people dislike first and middle names that end in ER together in the same name? [name]Just[/name] want to understand.
For me it’s to do with the flow of the name and it isn’t limited to just er endings - as a general rule I find first and middle names (and surnames) are not easy to say together if they end in the same sound.
For me, and it think everyone else. This has to do with the flow of a name. Very similar to why i dont like first names ending in the same letter that a middle/last name starts in. In that case, the name runs together, so instead of hearing [name]Helena[/name] [name]Amanada[/name] (random name), when its said aloud, it sounds like Hel-ay-na-manda. Like on long name. With the -er ending, its very similar, its doesnt flow very fell and sounds very repetive. A name such as [name]Skyler[/name] [name]Amber[/name], doesnt flow very well because it sounds like doubletaking back to the beginning with the same sound. Same general rule for names sounding to similar or rhyming.
Yeah, I’m just echoing what others have said at this point, but it doesn’t make for a name with good, or even fair, flow. It’s really the same for any end sounds. [name]Just[/name] as you wouldn’t want to do [name]Conner[/name] [name]Walker[/name], you wouldn’t want to do [name]Charlotte[/name] [name]Harriet[/name], [name]Lucy[/name] [name]Phoebe[/name], or even [name]Amanda[/name] [name]Louisa[/name], I’d argue. Usually, you end up with something that sounds just plain goofy ([name]Conner[/name] [name]Walker[/name]), abrupt ([name]Charlotte[/name] [name]Harriet[/name]), or overly melodious ([name]Lucy[/name] [name]Phoebe[/name]). I’m going to go out on a limb and say that, out of the four names I’ve just made, most people would say they like [name]Amanda[/name] [name]Louisa[/name] best - some people really like first and middle names to both end in -a, but I think you can do better in terms of balancing sounds. After all, you don’t want to end up with an “[name]Amelia[/name] [name]Bedelia[/name]” name, do you?
[name]Lemon[/name] 
I echo all of the above, but another aspect of the -er names is that they are usually derived from surnames. So [name]Tucker[/name] [name]Porter[/name] sounds like a law firm and not a person.
So an example would be [name]River[/name] [name]Alexander[/name] French…that doesn’t flow? I say it out loud and it sounds fine to me?
I think [name]River[/name] [name]Alexander[/name] is okay. Part of the issue is syllables. [name]River[/name] [name]Carter[/name] or [name]River[/name] [name]Miller[/name], for example, would sound off because both are two syllables and end in -er.
Yes, this is better than, say, [name]River[/name] [name]Tucker[/name], simply because of the syllabic count. However, and I know this isn’t what you’re asking, but I would caution against using [name]River[/name] with French as a last name. It begins to sound like a river named French, as in the [name]River[/name] [name]Nile[/name] - [name]Nile[/name] [name]River[/name]. Maybe I’m the only one who thinks this, though…
[name]Lemon[/name] 
[name]River[/name] [name]Alexander[/name] isn’t as bad since the -er sounds aren’t right on top of each other. What I think the problem is is that most -er names are two syllables so it’s x er x er, Errrrr is a sound people make when they don’t know what they want to say, so to me at least it makes me think of someone being nervous when talking. Plus a lot of people don’t like names with the same ending syllable together.